Eastern Asian endemic seed plant genera and their paleogeographic history throughout the Northern Hemisphere


*Author for correspondence. E-mail: <steven@flmnh.ufl.edu>.


We review the fossil history of seed plant genera that are now endemic to eastern Asia. Although the majority of eastern Asian endemic genera have no known fossil record at all, 54 genera, or about 9%, are reliably known from the fossil record. Most of these are woody (with two exceptions), and most are today either broadly East Asian, or more specifically confined to Sino-Japanese subcategory rather than being endemic to the Sino-Himalayan area. Of the “eastern Asian endemic” genera so far known from the fossil record, the majority formerly occurred in Europe and/or North America, indicating that eastern Asia served as a late Tertiary or Quaternary refugium for taxa. Hence, many of these genera may have originated in other parts of the Northern Hemisphere and expanded their ranges across continents and former sea barriers when tectonic and climatic conditions allowed, leading to their arrival in eastern Asia. Although clear evidence for paleoendemism is provided by the gymnosperms Amentotaxus, Cathaya, Cephalotaxus, Cunninghamia, Cryptomeria, Glyptostrobus, Ginkgo, Keteleeria, Metasequoia, Nothotsuga, Pseudolarix, Sciadopitys, and Taiwania, and the angiosperms Cercidiphyllum, Choerospondias, Corylopsis, Craigia, Cyclocarya, Davidia, Dipelta, Decaisnea, Diplopanax, Dipteronia, Emmenopterys, Eucommia, Euscaphis, Hemiptelea, Hovenia, Koelreuteria, Paulownia, Phellodendron, Platycarya, Pteroceltis, Rehderodendron, Sargentodoxa, Schizophragma, Sinomenium, Tapiscia, Tetracentron, Toricellia, Trapella, and Trochodendron, we cannot rule out the possibility that neoendemism plays an important role especially for herbaceous taxa in the present-day flora of Asia, particularly in the Sino-Himalayan region. In addition to reviewing paleobotanical occurrences from the literature, we document newly recognized fossil occurrences that expand the geographic and stratigraphic ranges previously known for Dipelta, Pteroceltis, and Toricellia.

Endemism, i.e., the confinement of taxa to a specified geographic region, occurs at various scales over the earth surface. The maiden hair tree (Ginkgo) and dawn redwood (Metasequoia) are just two examples of genera once widespread in the Northern Hemisphere that are now endemic to eastern Asia. Paleobotanical data confirm that a large number of plant genera now restricted to eastern Asia had broader geographic distribution in the geologic past. Fossil records in North America, Europe, and Asia document patterns of range expansion and reduction and eventual extirpation across large areas, sometimes leaving remnant populations only in eastern Asia (Manchester, 1999; Zhou & Momohara, 2005). In this review, we highlight paleobotanical records from the Northern Hemisphere that we consider to be valid representatives of the genera now confined to eastern Asia in order to illustrate former distribution patterns of these genera in each of the northern continents. These paleobotanical data show the importance of intercontinental dispersal between North America, Europe and Asia and indicate that the geographic source areas for the evolution of many genera remain in question.

Because some of the East Asian endemic plants have been considered to be phylogenetically primitive, and some are also known from the Asian fossil record, many authors have assumed that these genera originated in the area of their present distribution (e.g., Takhtajan, 1969). Wang (1988), for example, stated that the southern mountains of China may have been the cradle of endemic Chinese genera. However, the fossil record needs to be taken into consideration to evaluate such hypotheses. Many of the genera presently endemic to eastern Asia have excellent fossil records in North America and/or Europe, indicating that the source area of their evolution was not necessarily Asia. The paleobotanical literature abounds with reports of genera identified from the Tertiary of Europe and North America that are now living only in Asia. Some of these reports are well documented, with careful consideration of diagnostic characters of the genera; others are not. Many of the published reports are scattered in the geological literature on individual fossil floras and are not always easy to locate.

Although often dismissed because of its incompleteness, the fossil record provides hard data on former distribution patterns that cannot come from studies of extant organisms alone. Each fossil occurrence of a taxon, whether positioned within the current distribution area, or beyond the present geographic limits, provides additional data relevant to phytogeographic history. The purpose of this article is to review the paleobotanical records of genera that are now endemic to eastern Asia. This information can be used to track possible routes of intercontinental dispersal and to evaluate different hypotheses on the places of origin of these taxa. We believe that a compilation of reliable fossil accounts of these genera is necessary because there are numerous dubious reports in the literature that are not substantiated by fossils with sufficient diagnostic characters for reliable determination. In addition, many convincingly identified fossils that were previously published have escaped notice by subsequent workers.

A taxon may achieve endemic status through different historical pathways (e.g., Ying & Zhang, 1984; Ferguson et al., 1997). An incipient clade that has not had time to disperse broadly is classified as a “neoendemic”, whereas a remnant of a once more broadly distributed taxon, now extirpated from all of its former range with the exception of a small area of survival is termed “paleoendemic”. There is a gradient between these situations, but these two terms are conceptually useful. Sometimes a taxon may be inferred to be paleoendemic based on its location, ecological preferences, phylogenetic position and/or presence of “primitive” characters, but the fossil record plays an important role in confirming the status. Most of the examples highlighted in this treatment may be viewed as confirmed paleoendemics in view of their broader geographic distribution during the Tertiary than today.

1 Methods

To address the paleobotanical record of genera now endemic to eastern Asia, the first step was to arrive at a comprehensive listing of all the extant genera regardless of their fossil record. Many sources provide information and examples of plants endemic to eastern Asia, but none are fully comprehensive, because continuing taxonomic and phylogenetic work leads to revision. A taxon formerly considered to lie within the boundaries of “East Asia” may have to be excluded if additional research indicates that it has native populations existing outside the focus area, e.g., in Malesia, Europe, North America or western Asia. The concept of what constitutes a genus in a particular family also changes as phylogenetic studies provide improved understanding of the relationships of the species.

Initially, we focused our attention on genera of seed plants that are primarily restricted in their modern native distribution to China, Korea and Japan, although sometimes passing across these political boundaries into adjacent Vietnam, and India. The compilation of 243 endemic genera of China (Ying et al., 1993) is an excellent guide to the morphology and modern habitats of plants mostly restricted to China. In addition, to achieve a more comprehensive tally of genera endemic to the east Asian region, we must include also those genera that are endemic to Korea (about seven) and Japan (about 14; Xie, 1998), plus genera with occurrences shared in two or more of these areas. Wu (1998) listed 42 genera endemic to Korea plus Japan, the Bonin Islands, and the Ryukyu Islands. Summing these compilations gives an initial estimate of 298 genera of seed plants endemic to the Sino-Japanese flora. However, Qian et al. (2003a) listed 7 additional genera endemic to northeastern Asia including northeastern China, Korea and far eastern Russia, and many additional genera can be included in the East Asian flora when Sino-Himalayan taxa are included (Wu, 1998). Dr. Hong Qian kindly provided a more extensive listing of eastern Asian taxa as used in his comparative investigations with North America and other regions (Qian, 2001, 2002). The compilations of Ying et al. (1993), Wu (1998), Qian (2001; unpubl.), and Qian et al. (2003a, 2003b) aided in preparation of the current list of about 600 genera considered to be endemic to eastern Asia (Table 1). The list includes genera endemic to the broad area of eastern Asia extending from the Himalayas to Mongolia, eastern Russia (east of ca 80°E), Japan, and into Vietnam and Thailand. Criteria for acceptance of particular genera in the dataset were specified by Qian (2001); but we also excluded from the previous lists taxa now considered to extend beyond the boundaries under consideration here, while also introducing some genera that were not previously included (e.g., Amentotaxus, Boehmeriopsis, Baimashania, Burretiodendron, Codonopsis, Galitzkya). Malesia is treated as a separate province beyond the scope of this analysis. This listing of extant eastern Asian endemic genera is provided here with two goals in mind—1) to analyze in terms of the fossil representatives currently known, and 2) to provide a checklist of taxa that paleobotanists should learn to recognize to facilitate the identification of additional examples in the fossil record. General geographic distribution data were obtained from a variety of sources, commonly including Mabberley (1997) and Ying et al. (1993).

Table 1.  List of extant East Asian endemic genera of seed plants, showing familial assignment, modern geographic distribution and growth habit. Genera with accepted fossil records indicated in boldface font with asterisk (*). Genera grouped alphabetically by family. See material and methods for defining boundaries of “East Asia.”
FamilyGenusGeographic distributionGrowth habit#
  1. Genera in boldface and with asterisk (*) are known from the fossil record.

  2. Abbreviations: C, Central; N, North or northern; SC, South Central; SE, southeastern; W, Western; WC, west central. Himal, Himalalyas; Temp, temperate; trop, tropical, per herb, perennial herb; ann herb, annual herb; bien herb, biennial herb; shr, shrub; subshr, subshrub. Families are abbreviated by their first 5 characters.

AcantClarkeasiaNepal to Thailandshrub1
AcantHaplanthoidesChina (Yunnan)per herb2
AcantKudoacanthusChina (Taiwan)per herb3
AcantParagutzlaffiaSW Chinaper herb4
ActinClematoclethraWC Chinaliana5
AdoxaSinadoxaChina (Qinghai)per herb6
AdoxaTetradoxaChina (Sichuan)per herb7
AgavaAnemarrhena (=Terauchia)China, Korea, Mongoliaherb8
AnacaChoerospondias*NE India, N Thailand, SE China, Japantree11
AnacaDobineaHimal, S Chinashrub12
ApiacAcronemaSino-Himalper, bien herb14
ApiacApodicarpumE Japanherb15
ApiacArcuatopterusChinaper herb16
ApiacCarlesiaE Chinaper herb17
ApiacChaerophyllopsisW Chinaann herb18
ApiacChamaesiumHimal-W Chinaann, bien herb20
ApiacChangiumChina (Xizang, E)per herb21
ApiacChuanminshenChinaper herb22
ApiacCyclorhizaSW Chinaper herb23
ApiacDactylaeaC & E Chinaherb24
ApiacDickinsiaSW Chinaann herb25
ApiacDystaeniaKorea, Japanper herb26
ApiacHalosciastrumE Asiaherb27
ApiacHaplosphaeraBhutan, China, NE Indiaper herb28
ApiacHarrysmithiaChinaann herb29
ApiacMagadaniaNE Asiaherb32
ApiacMelanosciadiumChina (Guizhou, Sichuan)per herb33
ApiacNothosmyrniumChinaper herb34
ApiacNotopterygiumChinaper herb35
ApiacPhysospermopsisSC Chinaper herb36
ApiacPternopetalumE Asia, Himal, Chinaann, per herb37
ApiacPterygopleurumChina, Japan, Koreaper herb38
ApiacSaposhnikoviaChina, Korea, Mongolia, Russia (E Siberia)per herb39
ApiacSiniacaChina (Guizhou)herb40
ApiacSinocarumW Chinaper herb41
ApiacSinolimprichtiaSW Chinaper herb42
ApiacTongoloaSino-Himal, mainly in SW China, extending west to C Nepalper herb43
ApiacTordyliopsisBhutan, China, Nepal, Sikkimper herb44
ApociSindechitesChina, Laos, Thailandliana45
ApocyChunechitesSE Chinaclimbing shrub46
ApocyParepigynumChina (Yunnan, Guizhou)liana47
AracePinelliaChina, Japanherb48
AraliBoninofatsiaJapan (Bonin Islands)shrub49
AraliFatsiaChina (Taiwan), Japanshrub or small tree50
AraliHunaniopanaxChina (Hunan)epiphytic shrub51
AraliKalopanaxE Asiatree52
AraliMerrilliopanaxBhutan, Burma, W China, NE India, Nepaltree, shrub53
AraliSinopanaxChina (Taiwan)shrub54
AraliTetrapanaxS & SC Chinatree, shrub55
ArecaGuihaiaS China, N Vietnampalm57
ArecaSatakentiaRyukyu Islandspalm58
ArecaTrachycarpusHimal to E Chinatree59
AristSarumaC & E Chinaper herb60
AscleBelostemmaIndia, Chinatwining subshr61
AscleBiondiaChinaper twining herb; liana62
AscleDolichopetalumChinatwining shrub64
AscleGraphistemmaChina, Vietnamliana65
AscleJasminanthesChina, Thailandliana66
AscleMerrillanthusCambodia, Chinaliana67
AscleMetaplexisE Asialiana or scandent subshr68
AsclePentastelmaChina (Hainan)twining shr69
AscleSichuaniaChina (Sichuan)liana70
AscleTreutleraE Himalliana71
AsterSynurusChina, S Japan, Koreaper herb72
AsterAjaniopsisChina (Xizang)ann herb73
AsterAlfreda (=Xanthopappus)NW China, Mongoliaper herb74
AsterAtractylodesChina, Korea, Japan, Russia (Siberia)per herb75
AsterChaetoserisHimal, Chinaper to ann herb77
AsterCodonopsisE Asiaper herb78
AsterCremanthodiumHimal, S Chinaper herb79
AsterCrepidiastrumE Asiaann to per herb80
AsterCrossostephiumE Asiashrub81
AsterDendrocacaliaJapan (Bonin Islands)shrub82
AsterDicercocladosChinaper herb83
AsterDiplazoptilonSW Chinaper herb84
AsterDolomiaeaChina (Xizang), Himalper herb85
AsterDubyaeaHimal, W Chinaper herb86
AsterElachanthemumChina, Mongoliaann herb87
AsterEndocellionRussia (Siberia), E Asiaper herb88
AsterFarfugiumE Asiaherb89
AsterFilifoliumNE Asiaherb90
AsterFormaniaChina (Sichuan, Yunnan)shrub91
AsterHeteropappusC & E Asiaann herb92
AsterHeteroplexisChina (Guangxi)per herb93
AsterHololeionE Asiaper herb94
AsterKalimerisE Asiaper herb95
AsterMiricacaliaJapanper herb96
AsterMiyamayomenaJapanper herb97
AsterMyripnoisChina, Mongoliashrub98
AsterNannoglottisC & NC Chinaper herb99
AsterNemosenecioChina, Japanper herb100
AsterNotoserisSC & SE Asiaper herb102
AsterNoueliaChina (Yunnan, Sichuan)shrub, tree103
AsterOpisthopappusN Chinaper herb104
AsterPhaeostigmaChinaper herb, shr105
AsterRhynchospermumE & SE Asiaper herb106
AsterSheareriaS & SE Chinaann herb107
AsterSinacaliaChinaper herb108
AsterSinoleontopodiumChina (S Xizang)per herb109
AsterSoroserisHimal-W Chinaherb110
AsterStenoserisE Asiaper herb111
AsterStilpnolepisChina, Mongoliaann herb112
AsterSymphyllocarpusNE China, Korea, Russia (Siberia)ann herb113
AsterSyncalathiumChinaper herb114
AsterSyneilesisE Asiaper herb115
AsterSynotisSino-Himal, Chinaherb116
AsterTridactylinaRussia (E Siberia)ann herb117
AsterTugarinoviaMongoliaper herb118
AsterTurczaninoviaE Asiaherb119
BerbeDysosmaE Asiaper herb121
BerbeNandinaIndia to Japanshrub122
BetulOstryopsisC Chinashrub124
BoragAntiotremaSW Chinaper herb126
BoragBothriospermumTrop, NE Asiaherb127
BoragBrachybotrysNE China, Russia (Siberia)herb128
BoragChionocharisBhutan, China, NE India, Nepalper herb129
BoragIvanjohnstoniaNW Himal?130
BoragMaharangaBhutan, India, Nepal, Thailandper, bien herb131
BoragMetaeritrichiumChina (Xizang, Qinghai)ann herb132
BoragMicroulaBhutan, N and NE India, Nepal, Sikkimbien herb133
BoragSinojohnstoniaChinaper herb135
BoragThyrocarpusChina, Vietnamann herb136
BrassArcyospermaHimalper herb137
BrassBerteroellaHimal to Japan, Koreaann or bien herb138
BrassBorodiniaRussia (E Siberia)per herb139
BrassBaimashaniaChinaper herb140
BrassDipomaChinaper herb141
BrassEurycarpusChina (Xizang), Kashmirper herb142
BrassGalitzkyaW China, Mongolia, Kazakhstanper herb143
BrassGorodkoviaRussia (NE Siberia)per herb144
BrassHemilophiaSW Chinaper herb145
BrassLepidostemonBhutan, China, Nepal, Sikkimann herb146
BrassLignariellaBhutan, China, Nepal, Sikkimbien herb147
BrassMegadeniaChina, Russiaann or per herb148
BrassNeomartinellaChinaann herb149
BrassOreolomaChina, Mongoliaper herb150
BrassOrychophragmusChinaann, per herb151
BrassPachyneurumMongolia, Russia (Altai)per herb152
BrassPegaeophytonC Asia, Himal, to W Chinaper herb153
BrassPlatycraspedumChinabien, per herb154
BrassPycnoplinthusChina, Kashmirper herb155
BrassSinosophiopsisChina (Qinghai, Sichuan, Xizang)ann herb156
BrassSolms-laubachiaBhutan, China, Sikkimper herb157
BrassSynstemonNC Chinaann or bien herb158
BrassYinshaniaNC Chinaann, per herb159
BretsBretschneideraChina, Thailand, Vietnamtree160
CampaCyananthusHimalper herb163
CampaEchinocodonChinaper herb164
CampaHanabusayaKoreaper herb165
CampaLeptocodonHimalper herb166
CampaPlatycodonNE Asiaper herb167
CampuHomocodonS Chinaann herb168
CanabPteroceltis*N & C Chinatree169
CapriDipelta*C & S Chinashrub170
CapriHeptacodiumC & SE Chinasmall tree171
CapriKolkwitziaC & E Chinashrub172
CapriLeycesteriaHimal, SW Chinaclimbing shrub173
CapriSilvianthusE India to SE Asiashrub174
CapriWeigela*E AsiaShrub175
CaryoBrachystemmaHimalliana?/ann herb176
CaryoPsammosileneChinaper herb177
CelasMonimopetalumChina (Anhui, Jiangxi)climbing shr178
CelasPottingeriaIndia (Assam) to NW Thailandshrub179
CelasTripterygium*E Asiashrub180
CephaCephalotaxus*E Himal through China, Korea, Japan, Vietnam, Burma, Thailandshrub181
CerciCercidiphyllum*China, Japantree182
ChenoAcroglochinC & E China, Himalann herb183
ChenoArchiatriplexChina (Sichuan)ann herb184
ChenoBaoliaChinaann herb185
CircaCircaeasterNW Himal to NW Chinaann herb186
CommeStreptolirionBhutan, Burma, China, India, Japan, Korea, Laos, Sikkim, Thailand, Vietnamper herb187
ConvoDinetustrop Asiaherb twiner188
CrassKungiaChinaper herb189
CrassMeterostachysS Japan, S Koreaherb190
CucurActinostemmaIndia to Japanliana191
CucurEdgariaE Himalliana194
CucurGomphogyneE Himal to C China, SE Asialiana195
CucurHemsleyaE Asialiana196
CucurHerpetospermumHimal, Chinaliana197
CucurSchizopeponHimal, E Asialiana198
CupreCryptomeria*Japan, China (Fujian, Jiangxi, Sichuan, Yunnan, Zhejiang)tree199
CupreCunninghamia*China, N Vietnam, Laostree200
CupreFokieniaE China, N Laos, Vietnamtree201
CupreGlyptostrobus*SE Chinatree202
CupreMetasequoia*China (SW Hubei, NW Hunan, E Sichuan)tree203
CupreMicrobiotaNE Asiashrub204
CuprePlatycladusChina, Korea, E Russiatree205
CupreTaiwania*N Burma, China (SE Guizhou, SW Hubei, SE Sichuan, W Yunnan, Taiwan, SE Xizang)tree206
DiapeBerneuxiaHimalper herb208
DiapeDiplarcheE Himal, SW Chinashrub209
DipenDipentodonBurma, S Chinasmall tree210
EricaBryanthusJapan, Russia (Kamchatka)shrub211
EricaEnkianthusHimal to Japansmall tree212
EuphoCleidiocarponBurma, W Chinashrub214
EuphoDiscocleidionChina, Ryukyu Islandsshrub215
EuphoSperanskiaChinaper herb216
EupteEuptelea*India (Assam) to SW & C China, Japantree217
FumarDactylicapnosHimal to SE Asialiana218
GentiAllocheilosSW Chinaper herb219
GentiAllostigmaS Chinaper herb220
GentiAncylostemonChinaper herb221
GentiLatoucheaSE & SW Chinaper herb222
GentiLomatogoniopsisChinaann herb223
GentiMegacodonBhutan, SW China, India, Nepal, Sikkimper herb224
GentiPterygocalyxChina, Japan, Korea, Russiatwining per225
GentiVeratrillaBhutan, SW China, NE India, Sikkimper herb226
GesneBeccarindaBurma, S China, N Vietnamper herb227
GesneBoeicaChina, SE Asiaherb228
GesneBourneaChina (Guangdong, Fujian)per herb229
GesneBriggsiaE Himal, Burma, Chinaper herb230
GesneBriggsiopsisChinaper herb231
GesneCathayantheChina (Hainan)per herb232
GesneChiritopsisChinaper herb233
GesneConandronE China, Japanherb234
GesneCorallodiscusHimal-NW China, SE Asiaherb235
GesneDayaoshaniaChina (E Guangxi)per herb236
GesneDeinocheilosChinaper her237
GesneDidymostigmaS Chinaann herb238
GesneDolicholomaChina (Guangxi)per herb239
GesneGyrocheilosChinaper herb240
GesneGyrogyneChinaper herb241
GesneHemiboeaChina, S Japan, N Vietnamper herb242
GesneHemiboeopsisChina, Laosper herb243
GesneIsometrumChinaper herb244
GesneLagarosolenChina (S Yunnan)per herb245
GesneLeptoboeaBhutan, Burma, China, N India, Sikkim, Thailandherb, subshr246
GesneLoxostigmaBhutan, China, India, Burma, Nepal, Sikkim, N Vietnamper herb247
GesneLysionotusBhutan, China, Burma, N India, S Japan, Laos, Nepal, N Thailand, N Vietnamsubshrub, liana248
GesneMetabriggsiaChina (NW Guangxi)per herb249
GesneMetapetrocosmeaChina (Hainan)per herb250
GesneOpithandraChina, Japanper herb251
GesneOreocharisS China, Thailand, Vietnamper herb252
GesnePetrocodonChinaper herb253
GesnePlatystemmaBhutan, China, N India, Nepalper herb254
GesnePrimulinaChina (Guangdong)per herb255
GesnePseudochiritaChina (Guangxi)per herb256
GesneRehmanniaE Asiaherb257
GesneSchistolobosChina (Guangxi)per herb259
GesneTengiaChina (Guizhou)per herb260
GesneThamnocharisSW Chinaper herb261
GesneTitanotrichumChina, Japanper. herb262
GesneTremacronChinaper herb263
GesneWhytockiaChina (Guizhou, Taiwan, SE Yunnan)per herb264
GlaucGlaucidiumJapanper herb266
HamamChuniaChina (S Hainan)tree267
HamamCorylopsis*Bhutan to Japanshrub268
HamamDisanthus*E China, Japanshrub269
HamamFortunearia*Chinashrub, tree270
HamamLoropetalumChina, E & N India, Japanshrub, small tree271
HamamMytilariaChina, Laos, N Vietnamtree272
HamamSinowilsoniaC & NC Chinatree, shrub274
HamaTetrathyriumChina (Guangxi)tree, shrub275
HelwiHelwingiaBhutan, N Burma, China, N India, Japan, S Korea, Nepal, Sikkim, Thailand, N Vietnamshrub276
HydraCardiandraE Asiashrub/subshr277
HydraDeinantheC China, Japanherb278
HydraKirengeshomaChina, Japan, Koreaper herb279
HydraPileostegiaChina, E India, Japan, Ryukyu Islandsshrub evergreen, climbing280
HydraPlatycraterChina, Japanshrub281
HydraSchizophragma*China, Japan, Koreashrub282
IcaciHosieaW & C China, Japanliana283
IridaBelamcandaIndia to E Russia, Japanper herb284
IridaPardanthopsisN China, Mongoliaherb285
JuglaPlatycarya*China, Japan, Korea, Vietnamtree287
LamiaBostrychantheraChinaper herb290
LamiaCaryopterisE Asiaherb, subshr, shrub291
LamiaChelonopsisKashmir to E Asiaherb or shrub292
LamiaColquhouniaE Himal, SW Chinashrub293
LamiaComanthosphaceE Asiaherb294
LamiaHanceolaChinaper, ann herb296
LamiaHeterolamiumChinaann herb297
LamiaHolocheilaChinaper herb298
LamiaKeiskeaChina, Japanherb or subshr299
LamiaKinostemonC Chinaper herb300
LamiaLamiophlomisBhutan, China, India, Nepalper herb301
LamiaLeucosceptrumBhutan, Burma, China, India, Laos, Nepal, Vietnamshrub302
LamiaLoxocalyxChinaper herb303
LamiaMarmoritisChina, Indiaper herb304
LamiaNotochaeteBhutan, Burma, China, India, Nepalherb306
LamiaOmbrocharisChina (Hunan)per herb307
LamiaParalamiumBurma, China, Vietnamper herb308
LamiaPerillaIndia-Japanann herb309
LamiaRubiteucrisChina, Indiaherb313
LamiaSchnabeliaChinaper herb314
LamiaSinopogonantheraChina (Anhui, Zhejiang)herb315
LamiaSiphocranionBurma, China, India, Vietnamper herb316
LamiaSkapanthusChina (Sichuan, Yunnan)per herb317
LamiaSuzukiaChina, Japanherb318
LamiaWenchengiaChina (Hainan)subshr319
LardiAkebia*Temp E Asiatwiner320
LardiDecaisnea*E Himal, C Chinashrub321
LardiHolboelliaHimal, SE Asia, Chinaliana322
LardiSargentodoxa*China, Laos, Vietnamliana323
LardiSinofranchetiaC Chinaliana324
LardiStauntoniaBurma, China, N India, Japan, Vietnamliana325
LauraCinnadeniaE Himaltree326
LauraDodecadeniaS Himalshrub327
LauraParasassafrasHimal, Burma, W Chinatree328
LauraSinosassafrasChina (W Yunnan)small tree329
LegumAfgekiaBurma, China, Thailandclimbing shrub330
LegumChrysorrhizaS Chinaliana331
LegumCraspedolobiumW Chinaliana333
LegumGueldenstaedtiaSino-Himal to Siberiaper herb334
LegumMaackiaE Asiatree335
LegumSalweeniaChina (Sichuan, Xizang)shrub337
LegumSpongiocarpellaHimal to Chinaherb338
LilacNomocharisBurma, China, Indiaper herb339
LiliaAnemarrhenaChinaper herb340
LiliaCardiocrinumHimal, E Asiaherb341
LiliaChionographisChina, Japan, Koreaper herb342
LiliaDiurantheraChina (Guizhou, Sichuan, Yunnan)per herb343
LiliaHostaChina, Japan, Korea, Russiaper herb344
LiliaMilulaChina, Nepalper herb345
LiliaReineckeaChina, Japanper herb346
LiliaRohdeaChina, Japanper herb347
LiliaSpeiranthaChina (Anhui, Jiangxi, Zhejiang)per herb348
LiliaTheropogonBhutan, China, India, Nepal, Sikkimper herb349
LiliaTricyrtisHimal to E Asiaper herb350
LinacAnisadeniaHimal to C Chinaherb351
LinacReinwardtiaN India, Chinashrub352
MagnoKmeriaS China, Indochinatree353
MalvaBurretiodendronBurma, SW China, N Vietnamtree354
MalvaCorchoropsisE Asia, Japanann herb355
MalvaCraigia*SW Chinatree356
MalvaPityranthe (=Hainania)China (Guangxi, Hainan)tree357
MalvaReevesia ss*Himal to China (Taiwan)tree358
MastiDiplopanax*SW China, Vietnamtree359
MelasBrediaE & SE Asiaherb, shrublets362
MelasCyphothecaChina (Yunnan)shrub363
MelasFordiophytonS China, N Vietnamherb, subshr364
MelasStapfiophytonS Chinaherb365
MelasTigridiopalmaChina (Guangdong)herb366
MenisEleutharrhenaChina, India (Assam)liana368
MenisSinomenium*C China, Japanliana369
MusacMusellaChinaper herb371
MyrsiSadiriaE Himal, India (Assam)?372
MyrtaPyrenocarpaChina (Hainan)tree373
NymphEuryale*China, N India, Japanaquatic herb374
OlacaMalaniaChina (Guangxi, Yunnan)tree377
OrchiAceratorchisChina (Xizang)herb379
OrchiAmitostigmaChina, E Asiaherb380
OrchiAndrocorysIndia, E Asiaherb381
OrchiAnotaChina (Hainan)herb382
OrchiAnthogoniumE Himal to SE Asiaherb383
OrchiBletillaTemp E Asiaper herb385
OrchiBulleyiaHimal-SW Chinaper herb386
OrchiChangnieniaChinaper herb388
OrchiCremastraE Asiaherb389
OrchiDidicieaHimal to Japanherb393
OrchiDiphylaxChina, NE Indiaherb394
OrchiDiplandrorchisNE Chinaper herb395
OrchiEphippianthusJapan, Korea, Russia (Sakhalin)herb399
OrchiHancockiaE & SE Asiaherb400
OrchiHemipiliaHimal, E Asia, Thailandherb401
OrchiHolcoglossumChina (Taiwan), S Japanherb402
OrchiIschnogyneChinaper epiphyte herb403
OrchiMonomeriaHimal, SE Asiaherb404
OrchiNeofinetiaE Asiaherb405
OrchiNeogynaSE Asia, China, Indiaherb406
OrchiNothodoritisChina (Zhejiang)per herb407
OrchiOreorchisHimal to Japanherb408
OrchiOrnithochilusChina, India, Thailandherb409
OrchiOtochilusE Himal to SE Asiaherb410
OrchiPaniseaIndia to SE Asiaherb411
OrchiPorolabiumMongoliaper herb412
OrchiRisleyaHimal, W Chinaherb413
OrchiSedireaE Asiaherb414
OrchiSmithorchisChina (Yunnan)herb415
OrchiVexillabiumJapan, Koreaherb416
OrobaGleadoviaChina, Indiaherb417
OrobaPhacellanthusChina, Japan, Korea, Russian Far Eastherb418
OrobaPlatypholisJapan (Bonin Islands)herb419
OrobanMannagettaeaChina, Russiaherb420
PapapDicranostigmaHimal-W Chinaherb421
PapavEomeconE Chinaper herb422
PapavHylomeconTemp E Asiaper herb423
PapavMacleayaTemp E Asiaherb424
PinacCathaya*China (NE Guangxi, N Guizhou, S Hunan & SE Sichuan)tree426
PinacKeteleeria*China, Laos, Vietnamtree427
PinacNothotsuga*China (NE Guizhou, SW Hunan, N Guangdong, NE Guangxi, S Fujian)tree428
PinacPseudolarix*C & SE Chinatree429
PoaceAcidosasaS China, Vietnamherb430
PoaceAnisachneHimalper herb432
PoaceBrylkiniaChina, Japanherb435
PoaceChimonobambusaHimal to Japanbamboo436
PoaceFerrocalamusChinashrubby bamboo437
PoaceGaoligongshaniaChina (NW Yunnan)shrubby scrambling bamboo438
PoaceGelidocalamusS & C Chinashrub-bamboo439
PoaceLeptocannaChina (S Yunnan)bamboo441
PoaceMelocalamusBangladesh, Burma, S China, India (Assam)clump-forming climbing bamboo442
PoaceMonocladusChina (Guangdong, Guangxi, Hainan)undershrub443
PoacePhaenospermaChina, NE India, Japan, S Koreaherb444
PoacePleioblastusChina, Japan, Vietnambamboo446
PoacePseudodanthoniaNW Himal, W Chinaherb447
PoacePseudosasaChina, Japan, Koreashrub like-arborescent448
PoacePseudostachyumBhutan, Burma, China, NE India, Vietnamshrubby bamboo449
PoaceSasaChina, Japan, Korea, E Russiashrubby bamboo450
PoaceSemiarundinariaE China, Japanshrubby bamboo451
PoaceSetiacisChina (Hainan)per452
PoaceShibataeaSE China, SW Japanshrubby bamboo453
PoaceSinobambusaChina (Taiwan), Vietnambamboo454
PodocHydrobryumChina, S Japan, India (Assam), E Nepalper herb455
PodosTerniopsisChina (SW Fujian)per herb456
PolygParapteropyrumChina (SE Xizang)shrub457
PolygPteroxygonumChinaclimbing per herb458
PrimuBryocarpumE Himalper herb459
PrimuOmphalogrammaE Himal, N Burma, W Chinaper herb460
PrimuPomatosaceW Chinaper, bien herb461
PrimuStimpsoniaE Asiaann herb462
RanunAnemoclemaSW Chinaper herb463
RanunAnemonopsisJapanper herb464
RanunAsteropyrumBurma-Chinaper herb465
RanunBeesiaN Burma, W & SW Chinaper herb466
RanunCalathodesHimal-China (Taiwan)per herb467
RanunChieniaChina (Henan)herb468
RanunDichocarpumHimal, E Asiaherb469
RanunKingdoniaW & N Chinaper herb470
RanunMegaleranthisS Koreaherb471
RanunMetanemoneChina (N Yunnan)per herb472
RanunMiyakeaE Russia (Sakhalin)herb473
RanunParoxygraphisE Himalherb474
RanunSemiaquilegiaChina, Japan, Koreaper herb475
RanunSoulieaBhutan, Burma, China, Sikkimper herb476
RanunUrophysaChinaper herb477
RhamnBerchemiellaChina, Japantree478
RhamnHovenia*Bhutan, Burma, China, India, Japan, Korea, Nepaltree, shrub479
RosacChaenomelesE Asiashrub, small tree480
RosacDichotomanthesSW Chinashrub, tree481
RosacDocyniaHimal, SE Asiatree482
RosacEriobotryaHimal, E Asia, W Malesiatree, shrub483
RosacKerriaChina, Japanshrub484
RosacMaddeniaChina, Himaltree, shrub485
RosacPentactinaN Koreashrub486
RosacPotaniniaChina, Mongoliashrublet487
RosacPrinsepiaChina, Himalshrub488
RosacRhaphiolepisJapan, S Korea & S China to Thailand & Vietnamshrub, small tree489
RosacRhodotyposChina, Japan, Koreashrub490
RosacSorbariaTemp Asiashrub491
RosacSpenceriaChina (Sichuan, Yunnan)per herb492
RosacStephanandraE Asiashrub493
RosacStranvaesiaChina & Himal to SE Asiatree, shrub494
RosacTaihangiaChina (Henan, Hebei)per herb495
RubiaClarkellaHimal, Thailandherb496
RubiaDamnacanthusE Asiashrub497
RubiaDunniaIndia, Chinaundershrub498
RubiaEmmenopterys*Burma, China, Thailandtree499
RubiaHayataellaChina (Taiwan)herb500
RubiaIndopolysoleniaE Himal, Burma 502
RubiaLeptodermisHimal to Japanshrub503
RubiaLuculiaHimal, China (Yunnan), Vietnamshrub504
RubiaSinoadinaupper Burma, S to SW China, Japantree508
RubiaTrailliaedoxaSW Chinaundershrub510
RutacBoenninghauseniaIndia (Assam) to Japansap herb512
RutacBoniniaJapan (Bonin Islands)shrub513
RutacOrixaChina, Japan, Koreashrub514
RutacPhellodendron*E Asiatree515
RutacPoncirusChinatree, shrub516
RutacPsilopeganumChina (Hubei, Sichuan)per herb517
SalicIdesia*China, Japan, Koreatree518
SapinDelavayaSW China, N Vietnamshrub, small tree520
SapinDipteronia*C & S Chinatree521
SapinEurycorymbusS & SW China (include Taiwan)tree522
SapinHandeliodendronChina (Guangxi, Guizhou)tree523
SapinKoelreuteria*S China, Japan, perhaps Fijitree or shrub524
SapinPavieasiaS China, N Vietnamtree525
SapinSinoradlkoferaChina, Vietnamtree526
SapinXanthocerasChinalarge shrub or small tree527
SapotEberhardtiaSE Asia, N Borneo (Sabah), S Chinatree528
SauruGymnothecaC & SW China, N Vietnamper herb529
SaxafMukdeniaN China, Koreaper herb530
SaxifAstilboidesN Chinaherb531
SaxifOresitropheN & NE Chinaper herb532
SaxifRodgersiaHimal, E Asiaper herb534
SaxifSaniculiphyllumChina (Guangxi, Yunnan)per herb535
SaxifTanakaeaChina, Japanper herb536
ScropPhtheirospermumE Asiaper herb538
ScropDeinostemaE Asiaherb539
ScropHemiphragmaE China to W Himalherb540
ScropKashmiriaHimal 541
ScropLanceaBhutan, China, India, Mongolia, Sikkimper herb542
ScropMimulicalyxChinaper herb543
ScropMonochasmaChina, Japanper herb544
ScropOmphalothrixNE Asiaann herb546
ScropOreosolenHimal & Qinghai-Xizang Plateauper herb547
ScropPaulownia*China, Laos, Vietnamtree548
ScropPhtheirospermumE Asiaherb, ann or per549
ScropPseudobartsiaChinaann herb550
ScropPterygiellaChinaann herb551
ScropScrofellaChinaper herb552
ScropTriaenophoraChinaper herb553
ScropXizangiaChinaper herb554
SolanAnisodusTemp E Asiaherb555
SolanArchiphysalisE Asiaann herb556
SolanAtropantheChinaper herb, subshr557
SolanPhysaliastrumAsiashrub or herb558
SolanPrzewalskiaChinaper herb559
StachStachyurusHimal to Japanshrub/small tree560
StaphEuscaphis*Temp E Asiatree561
StyraHuodendronE Asiatree, shrub562
StyraPterostyrax*E Asiatree, shrub564
StyraSinojackiaChinatree, shrub565
TapisTapiscia*S & SE China, northernmost Vietnamtree566
TaxacAmentotaxus*China, Vietnamtree, shrub567
TheacApterospermaChinaevergreen tree569
TheacParapyrenariaChina (Hainan)small tree571
ThymeEdgeworthiaChina, Japanshrub573
ThymeStelleraC & E Asiaper herb or shrub574
ToricToricellia*Bhutan, China, N India, Nepal, Sikkimtree, shrub575
TrapeTrapella*China, Japan, Korea, Russia Far Eastaquatic herb576
TrochTetracentron*N Burma, NW & C China, Nepaltree577
TrochTrochodendron*southern Japan, southern Korea & China (Taiwan)tree578
UlmacHemiptelea*N China, Koreatree579
UrticAboriellaE Himalper herb580
UrticArchiboehmeriaS China-SE Asiashrub581
UrticNanocnideTemp E Asiaper herb582
UrticPetelotiellaNE Vietnamherb583
ValerTriplostegiaSE Asiaper herb585
VelloAcanthochlamysChinaper herb586
VerbiTsoongiaBurma, China, Vietnamshrub/small tree587
VitacYuaChina, Indialiana588
ZingiParamomumChina (Yunnan)per herb591
ZingiPyrgophyllumChina (Sichuan, Yunnan)per herb592
ZingiRoscoeaHimal, W Chinaherb593
ZingiSiliquamomumChina, Vietnamherb594
ZygopTetraenaChina (Nei Mongol)shrub595

Previous surveys of paleobotanical literature that were used in preparing this summary include LaMotte (1952) and Taylor (1990) for North America, Kirchheimer (1957) and Mai (1995) for Europe, Tanai (1994), Liu et al. (1996), and Momohara (1997) for Asia, Manchester (1999) for the Northern Hemisphere records, and Takhtajan (1963) and Collinson et al. (1993) for worldwide records. These reviews were used as initial guides to the literature; we did not automatically accept the reports presented in these references, but evaluated the reports from primary literature based on published descriptions and illustrations, and where feasible we reexamined the cited specimens.

In evaluating the validity of paleobotanical records, we accepted genera reported in the paleobotanical literature only if: (1) the organ(s) and morphological/anatomical features preserved and described could be considered truly diagnostic to the genus indicated, and (2) the description was accompanied by illustrations showing the diagnostic characters, or we were able to examine the original specimens and agreed with the published assignments. Although there are many extinct genera present in the Cretaceous and Tertiary, we limited our scope in this study to fossils that could be placed with confidence in extant genera. In addition to summarizing occurrences from earlier literature, we document with illustrations new, previously unrecorded occurrences of Dipelta (a new record from the Eocene of Mississippi), Pteroceltis (new record from the Eocene of Tennessee) and Toricellia (the oldest known record, from the Paleocene of North Dakota, USA).

For the examination of fossil specimens, we consulted the following collections: University of California, Berkeley; Denver Museum of Natural History; Florida Museum of Natural History, University of Florida; Peabody Museum of Natural History, Yale University; United States National Museum, Washington, DC; Burke Museum of Natural History and Culture, Seattle; Field Museum, Chicago; Natural History Museum, London; Czech National Museum, Prague; Simon Fraser University, Burnaby, BC, Canada; Senckenberg Museum of Natural History, Frankfurt; Staatliche Museum fur Naturkunde in Stuttgart; Humboldt Museum, Berlin; Geological Institute and Geological Museum, Moscow; National Museum of Nature and Science, Tokyo; Institute of Botany, Chinese Academy of Sciences, Beijing; the Shanwang Museum, Shandong.

Institutional abbreviations applied in the figure captions for fossil specimens include, BM (Natural History Museum, London), CMPH (Paleobotanical Herbarium, Institute of Botany, Chinese Academy of Sciences, Beijing), FMNH (Field Museum, Chicago), GINRAS (Geological Institute, Russian Academy of Sciences, Moscow), KRAM-P (Palaeobotanical Museum of the W. Szafer Institute of Botany, Polish Academy of Sciences, Krakow, Poland, SFU (Simon Fraser University), SMNS (Staatliches Museum für Naturkunde, Stuttgart, Germany), UF (Florida Museum of Natural History, University of Florida), USNM (United States National Museum of Natural History, Smithsonian Institution, Washington, DC), and UWBM (Burke Museum of Natural History and Culture, University of Washington).

The morphology of extant genera was studied for comparison with the fossils, using freshly collected specimens from our own field work when possible. Otherwise, we relied on herbarium specimens observed and photographed at A, GH, K, MO, PE, with supplemental data from plants cultivated in botanical gardens.

We maintain the long-standing useful stratigraphic term, “Tertiary,” for the Post-Cretaceous, Pre-Quaternary interval, despite the current notion of many geologists who prefer to replace the term with the more cumbersome phrase “Paleogene and Neogene.” The million-year chronology of Tertiary epochs follows Gradstein et al. (2005). The precise age of many floras cannot be specified due to lack of good stratigraphic control or radio-metric dates. We tentatively accept the assignments given by the most recent authors, although in some cases there continue to be disagreements among different investigators. We attempt to be conservative in the positioning of stratigraphic ranges; hence the ranges presented here are often shorter (begin later) than those indicated by other authors.

2 Results

In the sections that follow, we attempt to summarize the fossil and modern distribution of each genus, organized by gymnosperms (dipicted graphically in Table 2) first followed by angiosperms (Table 3), treated alphabetically by family.

Table 2.  Former and present geographic distribution of Ginkgo and coniferous genera now endemic to eastern Asia Thumbnail image of
Table 3.  Former and present geographic distribution of angiosperm genera now endemic to eastern Asia (Abbreviations as indicated for Table 2) Thumbnail image of

2.1 Gymnosperms

2.1.1 Cephalotaxaceae

Cephalotaxus has about 10 living species ranging from the eastern Himalaya through China, Korea, Japan, Vietnam, Burma, and Thailand. The fossil record indicates that the genus was widespread across the Northern Hemisphere during the Tertiary. In Asia, the genus is known from the Paleogene of northeastern China (leaf remains with epidermal preservation, He & Tao, 1997), and from the Pliocene and Pleistocene of Japan (seed remains, Miki, 1958). European remains occur in the Miocene and Pliocene (Givulescu, 1973; Meller, 1998). Cephalotaxus miocenica (Kräusel) Gregor is recognized on the basis of seeds from brown coal deposits in the Mio-Pliocene of Germany (summarized by Meller, 1998), and C. rhenana Gregor seeds occur in the Pliocene of Italy (Martinetto, 2001b). Species known from leaf remains with well preserved epidermal characters include C. messelensisWilde (1989) from the Middle Eocene of Messel, Germany, C. parvifolia (Walther) Walther & Kvaček from the Early Oligocene of Kundratice, North Bohemia (Kvaček & Walther, 1998) and the Early Oligocene of Seifhennersdorf, Germany (Walther & Kvaček, 2007), C. harringtoniana fossilis K. Koch (Mai & Walther, 1978) from the Neogene sites, and C. pliocenica Mädler from the Pliocene of Germany (Mädler, 1939). In North America, the genus is confirmed by leaves with epidermal characters in C. bonseri (Knowlton) Chaney & Axelrod from the Miocene of Oregon and Idaho (see Kvaček & Rember, 2000).

2.1.2 Pinaceae

Four genera of the pine family are endemic to eastern Asia today: Cathaya, Keteleeria, Nothotsuga and Pseudolarix.

Cathaya has one species, C. argyrophylla Chun & Kuang, living in the mountains of southwestern and central China in northeastern Guangxi, northern Guizhou, southern Hunan, and southeastern Sichuan (Wu & Raven, 1999). Its bisaccate pollen is distinguished from that of other Pinaceae by the sacci originating at the margins of the corpus, and by the presence of irregularly arranged spinules on both the corpus and sacci, best seen under a scanning electron microscope (Liu et al., 1997; Sivak, 1975). Based upon pollen records that are commonly misinterpreted as Podocarpus, reviewed by Liu et al. (1997) and Liu & Basinger (2000), Cathaya has occurrences ranging from the Late Cretaceous to Pleistocene in Asia, from the Late Cretaceous to Miocene of North America, and from the Paleocene to Pleistocene in Europe. In Europe, Cathaya cones have been identified from the Miocene of Germany, Greece, and France, and from the Pliocene of Germany and Italy (references in Martinetto, 1998; Mai & Velitzelos, 2007). The determination to this genus is supported by leaves with cuticle from the Late Oligocene of Kleinsaubernitz, Germany (Walther, 1999), and by both well preserved cones and anatomically preserved leaves from the Lower Miocene of Wiesa near Kamentz, Saxony, Germany (Kunzmann & Mai, 2005) and by cones from the Pliocene of Italy (Martinetto, 2001b). Well preserved cones and leaves are also recognized from the Miocene of Idaho, USA (Kvaček & Rember, 2000). The genus was confirmed in the Pliocene of Japan based on pollen investigated both by light and scanning electron microscopy (Saito et al., 2001).

Keteleeria has three to five extant species in the broadleaved evergreen forests of China, Laos, and Vietnam. Keys distinguishing the seeds of Keteleeria from those of other Pinaceae are provided by Wolfe and Schorn (1990) and Frankis (1989). The genus is known based on distinctive seeds from the Eocene of Quilchena flora of British Columbia (compare Figs. 1 & 2) and Oligocene of Oregon (Meyer & Manchester, 1997). Seeds, needles and male strobili with in situ pollen of Keteleeria are known from Upper Oligocene to Miocene sediments of Central Europe (e.g. Kräusel, 1938; Kirchheimer, 1942; Mai, 1964; Mai, 1995; Mai, 1997; Kunzmann & Mai, 2005). Impressions of a cone, seeds and leafy shoots have been recorded from the Miocene Shanwang flora (Wang et al., 2006) and Pliocene of Japan (Miki, 1957). In our opinion, Tanai's K. ezoana (1961) needs further examination, including comparison with Pseudolarix.

Figure 1–14.

1, 2. Pinaceae: Seeds of Keteleeria. 1. Seed from early Eocene Quilchena flora, British Columbia, Canada, photo courtesy of Rolf Mathewes, SFU s.n. 2. Seed of extant K. fortunei Carr., Zhejiang, China, PE 1600449. 3–11. Anacardiaceae: Extant and Eocene examples of Choerospondias.3–5.Choerospondias axillaris.3. Lateral view showing apically positioned germination valves. 4. Apical view showing five germination valves. 5. Transverse section showing five locules with surrounding lacunae. 6–9.Choerospondias sheppeyensis (Reid & Chandler) Chandler, Early Eocene London Clay Formation, Herne Bay, Kent, England, Holotype, BM v30105. 6. Lateral view of abraded exterior, showing a germination valve at upper left. 7. Same specimen, in transverse section, showing five locules. 8. Same specimen as 6, rotated to show longitudinally fractured surface with smooth locule lining visible at left. 9. Another specimen of C. sheppeyensis, apical view showing five germination valves, BM v30101, figured Chandler 1961, pl. 21, fig. 29. 10. Enlarged cross section of C. axillaris. 11. Enlargement from 7, showing five locules with intervening parenchyma-filled lacunae. 12–14. Caprifoliaceae: Modern and fossil fruits of Dipelta. 12. Extant Dipelta floribunda, Arnold Arboretum, Massachusetts, UF ref. coll. 146. 13. Holotype of Dipelta europaea Reid & Chandler from the Early Oligocene Bembridge flora of southern England, BM v17621. 14.Dipelta sp. from Middle or Late Eocene of Bovay Clay Pit, Marshall Co., Mississippi, UF 15737–49026. Scale bars=1 cm. The bar in Fig. 2 applies to Figs. 1 and 2, the bar in Fig. 9 applies to Figs. 3–11.

Nothotsuga Hu ex C. N. Page has a single extant species, N. longibracteata (W. C. Cheng) Hu ex C. N. Page (1988) distributed in northeastern Guizhou, southwestern Hunan, northern Guangdong, northeastern Guangxi and southern Fujian, China. Formerly treated as a species of Tsuga, it is distinguished by radially spreading leaves with stomatal lines on both upper and lower leaf surfaces and erect seed cones (Wu & Raven, 1999). Nothotsuga was recently recognized based on the distinctive epidermal anatomy of needles from the upper Lower or lower Middle Miocene of the Hasenberg clay pit near Kamenz, Saxony, Germany (Kunzmann & Mai, 2005).

Pseudolarix is restricted in modern distribution to central and southeastern China, with only one species, P. amabilis (J. Nelson) Rehder, living at 100–1500 m in elevation (Wu & Raven, 1999). Pseudolarix has an excellent fossil record in the Northern Hemisphere based on its distinctive seeds, cones, and foliage, with earliest records in the Cretaceous of Asia and North America followed by Oligocene establishment in Europe (LePage & Basinger, 1995, Gooch, 1992). It is also documented by well preserved seed cones, seeds, foliage and brachioblasts from the Middle Eocene of Arctic Canada (LePage & Basinger, 1995). Seed cone scales and seeds of P. schmidtgenii Kräusel were recovered, for example, from the Middle Miocene of Oberlausitz, Saxony, Germany (Czaja, 2001). The genus became extinct in North America by the middle to late Early Miocene (LePage & Basinger, 1995), and in Europe after the Pliocene (Martinetto, 2001b). It is documented in the Middle Miocene to Pliocene of Japan (Tanai, 1961).

2.1.3 Ginkgoaceae

Although possibly wild trees of Ginkgo biloba have been found in northeastern Zhejiang Province, the species has a history of cultivation in other provinces of China, such that it is no longer possible to deduce the prehuman natural range of the species (Wu & Raven, 1999). Ginkgo is easily recognized by its fanshaped leaves with subparallel dichotomizing and anastomosing venation, and ovoid drupe-like seeds. The cuticle is relatively resistant and often is preserved on fossil specimens, providing additional diagnostic characters. The record of Ginkgo and closely related genera in the Northern Hemisphere extends back to the Jurassic. Its record in the Tertiary indicates relatively late confinement to Asia. Tertiary records in North America extend from the Paleocene of Rocky Mountains and Great Plains (Brown, 1962; Manum, 1966; Crane et al., 1990; McIver & Basinger, 1993) and Middle Eocene of Pacific Northwestern North America (Mustoe, 2002) to the Miocene of Oregon (Chaney, 1920). In Europe it is known also from the Paleocene (Boulter & Kvaček, 1989) to the Early Pliocene (Tralau, 1968; Hably & Kvaček, 1997) and mid-Pliocene (Mädler, 1939). A rare Late Miocene record from Saxony, Germany was documented by Walther (2002). In Asia, Ginkgo is well documented from the Paleocene Amur region (Krassilov, 1976) of Koryak Upland, Russia (Golovneva, 1994), the Eocene of Fushun (Endo, 1942; WGCPC, 1978), and Huadian (Manchester et al., 2005), China, and from the Eocene to Early Pleistocene of Japan (Uemura, 1997; Yamakawa, 2000). A world-wide review of the stratigraphic distribution of this genus was presented by Tralau (1968) and a more detailed treatment of the Asian records by Uemura (1997). Although Tertiary leaves similar in appearance to extant G. biloba are usually placed in the fossil species G. adiantoides Heer, Mustoe (2002) found no significant differences and assigned Eocene leaves to the extant species. The resistant cuticle is often preserved in fossils, and this genus has therefore been a taxon of special interest in assessments of changing CO2 levels through geologic time.

2.1.4 Sciadopityaceae

This family, with only one extant genus, Sciadopitys, is endemic to Japan with the single species, S. verticillata (Thunb.) Sieb. & Zucc. The earliest fossil record is a seed cone of the family from the Upper Cretaceous of Hokkaido, Japan (Saiki, 1992). Christophel (1973) recognized Sciadopitys-like shoots and leaves from the Paleocene Smokey Tower locality in western Alberta, Canada which he referred to the fossil genus, Sciadopitophyllum. The long, strap-like leaves of this fossil are attached in apparent whorls subtended by groups of scale leaves, and other scale leaves are borne in loose spirals on the shoots between whorls, as in the extant genus. The branch buds in the axis of scale leaves are in a much less acute angle in Sciadopitophyllum than in extant Sciadopitys, and the flange of scale leaves found below the newly developed bud in the extant genus is not found in the fossil material. However, Christophel (1973) reasoned that these differences probably do not negate the possibility of a close relationship between the fossil genus and extant Sciadopitys. In addition, the extant genus Sciadopitys has been confirmed by the epidermal anatomy of well preserved fossil leaves from the Tertiary of Europe (Florin, 1963; Weyland et al., 1967), e.g., S. tertiaria from the Lower and Middle Miocene browncoal of Lusatica, Germany (Dolezych & Schneider, 2005) and Late Miocene of Japan (Uemura, 1986).

2.1.5 Taxaceae

Amentotaxus, with five or six extant species in China and Vietnam, has an excellent fossil record in North America and Europe. It is readily recognized by its broad needle-like leaves with a pair of prominent stomatal bands and distinctive epidermal anatomy (Ferguson et al., 1978). Amentotaxus extends from the Upper Cretaceous (Santonian) to Miocene in North America (Kvaček & Rember, 2000) and from the Paleocene to Upper Miocene of Europe (Ferguson et al., 1978; Jähnichen, 1990).

2.1.6 Cupressaceae (incl. Taxodiaceae)

This family includes multiple genera now endemic to East Asia, including Metasequoia, Cunninghamia, Cryptomeria, Glyptostrobus and Taiwania.

Metasequoia, which grows natively in southwestern Hubei, northwestern Hunan, and eastern Sichuan, has become famous as an example of a genus that was formerly widespread in the Northern Hemisphere but is now native only to China. The generic name was established based on fossil remains in Japan (Miki, 1941) prior to discovery of living trees in central China. Subsequently, the dawn redwood has been recognized to have an excellent Cretaceous and Tertiary record in Asia and North America. A comprehensive review of the modern genus and its Late Cretaceous to Neogene fossil record was provided by LePage et al. (2005). Particularly detailed reports of Metasequoia foliage and cones from the Paleocene of Alberta, Canada were provided by Stockey et al. (2001) and from the Paleocene Wuyun Formation of northeastern China by Liu et al. (1999). The record is poor in Europe, except for the occurrences in the Paleocene of Scotland and Eocene of Spitsbergen (Boulter & Kvaček, 1989).

Cryptomeria has a single species today native to Japan and in Fujian, Jiangxi, Sichuan, Yunnan, and Zhejiang provinces of China. The fossil species C. kamtschatica Cheleb. is based on leafy twigs from the Eocene of Kamchatka (Budantsev, 1997). In Europe C. rhenana Kilpper is known from the Lower and Middle Miocene based on dispersed cuticles (referred to Enormicutis conferta Schneider by Dolezych and Schneider, 2005) and from the Late Miocene of Rhein region based on seed cone, seeds, and foliage with cuticle (Kilpper, 1968). The genus extends to the Early and Middle Pliocene of Italy based on cones, seeds and associated twigs (Martinetto, 1998, 2001a). It is also known from the Miocene to Pleistocene of Japan (Miki, 1950; Nishida & Uemura, 1977) and Miocene of Primorye (Klimova, 1975).

In the morphology of foliar twigs, it may be difficult to distinguish Cryptomeria from other taxodioid Cupressaceae. A comparison of epidermal anatomy with that of other genera, to aid in the identification of fossil cuticles, is provided by Ma et al. (2007). Ferguson (1967) accepted the record of C. sternbergii by Gardner (1886) based on a branched twig with attached cones from the Paleocene of Northern Ireland, as a valid example of the genus. However, Boulter and Kvaček (1989) referred Gardner's Cryptomeria to Glyptostrobus based mainly on cuticle morphology (see below).

Cunninghamia has one species today occurring in mixed mesophytic and broad-leaved evergreen forests of China and in northern Vietnam and Laos at 200 to 2800 m (Wu & Raven, 1999). It is represented in the fossil record by cones, seeds, and foliage from the Eocene to Miocene of western North America (reviewed in Meyer & Manchester, 1997; Kvaček & Rember, 2000), by foliage twigs with well preserved epidermal anatomy and cones in the upper Lower Oligocene to Pliocene of Europe (reviewed Kovar, 1982; Walther, 1989, 1999), and by leafy twig impressions from Eocene of Kamchatka (Budantsev, 1997). Foliar twigs are also known from the Eocene to Pleistocene of Japan (Matsuo, 1963; Horiuchi, 1996; Miki, 1950).

Glyptostrobus is native today only in southeastern China and Vietnam with the single species G. pensilis, but it was widespread in the Tertiary. The paleobio-geographic history of the genus was reviewed recently by LePage (2007), who accepts reports as old as the Aptian stage of the Cretaceous from western Canada and Greenland, and later Cretaceous records both in Asia and North America. In contrast to Metasequoia, which is almost lacking in the European Tertiary, Glyptostrobus is known from numerous European localities, ranging from the Paleocene (Boulter & Kvaček, 1989) to the Pliocene (Mai, 1995; Martinetto, 1998). Beautifully preserved cones and seeds are illustrated as G. europaea (Brongn.) Unger by Meller (1998) from the Lower Miocene of Steiermark, Austria. In North America, Glyptostrobus is well represented in the Paleocene to Eocene of the Rocky Mountain region (Brown, 1962), and in the Miocene of Idaho, Oregon and Washington (Brown, 1936; Chaney & Axelrod, 1959; Fields, 1996). Glyptostrobus europaeus twigs with attached cones are known in the Eocene to Pliocene of Japan (Tanai, 1961) and a permineralized cone was described from the Middle Miocene of central Hokkaido, Japan (Matsumoto et al., 1997).

Taiwania has one species native to southeastern Xizang, western Yunnan, SE Sichuan, SW Hubei, SE Guizhou, Taiwan, and northern Burma. Vegetative shoots bearing cones were described and illustrated as T. schaeferi from the Paleocene of Spitsbergen by Schloemer-Jäger (1958) and were considered to agree in all respects with those of the modern genus (Ferguson, 1967). Foliar branches with well preserved cuticle have been recognized from the Oligocene-Miocene Weisselster Basin (Mai & Walther, 1991) and from the Late Oligocene of Kleinsaubernitz (Walther, 1999). Kilpper (1968) described a species based on a seed cone and leaf with cuticle from the Late Miocene of Rheinland, and Martinetto (1998) described additional examples from the Pliocene of Italy. The genus is represented in the Neogene of Japan by foliage shoots from the Middle Miocene to Pliocene of Hokkaido and Honshu (Tanai, 1961) and by cones and shoots from the Pliocene of Honshu (Miki, 1954).

Thujopsis. Shoots of Thujopsis were reported from the Late Miocene to Pleistocene of Japan (Huzioka & Uemura, 1973). As yet, no fossil cones or seeds have been found for confirmation.

2.2 Angiosperms

2.2.1 Anacardiaceae

Choerospondias, of the tribe Spondiadeae, with one species distributed in northeastern India, southeastern China and northern Thailand, has distinctive pentalocular, operculate endocarps (Figs. 3–5, 10) readily identifiable as fossils. Well-preserved fruits of C. sheppeyensis (Reid & Chandler) Chandler are known from the Lower Eocene London Clay flora of southern England (Figs. 6–9, 11; Reid & Chandler, 1933; Chandler, 1961). In Japan, fruits of Choerospondias are known from the Middle Miocene of central Honshu (reported as Spondias, Miki & Sakamoto, 1961), the Pliocene Osaka Group of southwestern Honshu (Fig. 14 in Momohara, 1989) and from several Pliocene localities in central Honshu (as Spondias in Miki, 1941).

2.2.2 Caprifoliaceae

Dipelta has three living species of deciduous shrubs which occur in southwestern and northwestern China, in forest, shrubs, or hill slopes at altitudes from 600 to 3600 m. Dipelta fruits are elongate, with persistent epigynous sepals and enlarged bracts that function in wind dispersal (Fig. 12). The characteristic bract-winged fruits have long been known from the Early Oligocene of England (Fig. 13; Reid & Chandler, 1926). In addition, a single specimen from the Middle or Late Eocene of Mississippi, USA conforms in arrangement and venation of the bracts and in the narrow persistent pedicel to extant Dipelta (Fig. 14).

Diplodipelta, an extinct genus known from several Late Eocene to Middle Miocene sites in the western United States appears to be the sister genus to Dipelta (Manchester & Donoghue, 1995). Both genera have similar elongate fruits with epigynous sepals, but they differ in the morphology of their dispersal units. Whereas the dispersal units of Dipelta consist of a single fruit subtended by three enlarged bract wings, Diplodipelta dispersal units consist of a pair of fruits subtended by the three bract-wings. The morphological similarity between North American Diplodipelta and the Euro-Asian Dipelta suggests early Tertiary geographic continuity. Fruits of Dipelta and Diplodipelta have not been recognized from the Asian fossil record.

Weigela is a genus of deciduous shrubs native to northern China, Korea and Japan. It is distinguished from the related North American genus Diervilla by structure of the flowers and fruits and by the presence of membranous wings on the seeds (Lańcucka-Środoniowa, 1967). Seeds are known from the Miocene and Pliocene of Poland (Lańcucka-Środoniowa, 1967), the Miocene of Mammoth Mountain, eastern Russia, the Oligocene and Miocene of western Siberia (Dorofeev, 1957, 1963), and the Miocene of Denmark (Friis, 1985). The fossil seeds of this genus resemble those of extant species of section Utsugia, and W. maximowiczii which have a thin membranous marginal wing formed of elongated thin-walled cells. Friis (1985) carried out comparative SEM studies and noted that the Miocene seeds are particularly similar to those of extant W. hortensis, but differ in having much thinner cell walls. Pollen of Weigela has been recognized by light and scanning electron microscopy from the Lower Miocene of Oberdorf, Austria (Meller et al., 1999), but it was not explained how this pollen type may be distinguished from other genera of the family having similar spiny pollen.

2.2.3 Cannabaceae (incl. Celtidaceae)

Pteroceltis has one species, P. tatarinowii of northern to south-central China and Mongolia, found at altitudes of 100 to 1500 m. It usually grows in valleys and streams of limestone mountains in sparse forest. The fruits consist of a globose endocarp with a pair of finely striate lateral wings (Fig. 15). Perianth parts sometimes persist at the junction of the narrow pedicel with the fruit. Pteroceltis tertiaria Weyland is recognized from fruits in the Late Oligocene of Rott, Germany (Fig. 16; Weyland, 1937; Manchester, 1989). These have larger wings than the living species, but appear to be identical to the extant species in wing venation and morphology of the fruit body. Similarly large fruits of Pteroceltis knowltonii (Berry) comb. nov. occur in the Middle Eocene of Puryear, Tennessee (Fig. 17). This species, along with one from the Middle Eocene of Republic, Washington (Fig. 18; Pigg & Wehr, 2002) indicate that the genus was formerly distributed in North America as well as Eurasia. Pteroceltis shanwangensis Tao & Sun from the Miocene Shanwang flora (Sun et al., 1999) is based on a leaf very similar to that of extant P. tatarinowii (see especially, Sun et al., 1999, pl. 6, fig. 4). The leaf could alternatively represent a species of Celtis.

Figure 15–18.

Cannabaceae: Modern and fossil fruits of Pteroceltis. 15. Extant Pteroceltis tartarinowii, Botanical Garden, Chinese Academy of Sciences, Beijing. 16.P. tertiara Weyland, Oligocene of Rott, Germany. Univ. Köln 1836. 17.Pteroceltis knowltonii (Berry) comb. nov., Middle Eocene of Puryear, Tennessee, USNM 35794 (holotype, Orig. Dodonaea knowltoniBerry, 1916). 18.Pteroceltis sp. Middle Eocene of Republic, Washington, UWBM 96986. Scale bars calibrated in mm.

Pteroceltis has also been recognized in the Neogene of Korea and Japan, but these records are in need of re-consideration. Oishi and Huzioka (1942) described two winged fruits with photos and drawings “Pteroceltis sp. cfr. P. tartarinowii Maxim.” from the “Miocene” Kokangen Engelhardia bed of North Korea, and “Pteroceltis? sp.” from the Miocene of Abura, Hokkaido, Japan. The published illustration of the Abura fruit resembles a fruit of Pterocarya (Juglandaceae), but Oishi and Huzioka stated that it differs completely from that genus in features of the central seed body. We have not observed the specimen and are not sure whether it has distinct venation in the wings (a difference from Pteroceltis), or a simple striate pattern (consistent with Pteroceltis). In their subsequent treatment of the Abura flora, Tanai and Suzuki (1963, p. 110) regarded Oishi & Huzioka's Pteroceltis? sp. as Pterocarya ezoana). Because Tanai and Suzuki did not mention the feature of fruit/seed body, and Oishi and Huziokas' original figure (1942, fig. 1) was retouched, re-examination of the original specimen is necessary to confirm or reject this identification.

Oishi and Huzioka's (1942) Kokangen specimen, “Pteroceltis sp. cf. P. tartarinowii Maxim.” curiously is not mentioned in Huzioka's later treatment of the Korean flora (1972). However, the original fragmentary Kokangen specimen appears similar to a more complete specimen named Carpites kungshimensisHuzioka (1972, p. 76, pl. 12, figs. 6, 7) from another locality, Kungshim, in the same district of North Korea, and in the same stratum (“Engelhardtia bed”) as Kokangen. It looks very likely to be Pteroceltis—consistent in the globose shape of the nut, the persisting narrow pedicel, and the wing shape and lack of wing venation. The age of these localities, whether Middle Miocene as originally published, or Oligocene, is still in debate. To be conservative in placement, we have indicated this occurrence as early Middle Miocene in the stratigraphic table (Table 3).

2.2.4 Celastraceae

Tripterygium is a genus of lianas and scandent shrubs distributed from eastern China to Japan. The distinctive winged fruits were recognized along with fossil leaves attributed the genus by Ozaki (1991) from the Pliocene Kabutoiwa Formation of Central Honshu, Japan. Other reports of this genus have turned out to be examples of Craigia fruits (see Kvaček et al., 2005).

2.2.5 Cercidiphyllaceae

Cercidiphyllaceae are represented by one extant genus with two species native to China and Japan (Spongberg, 1979). Cercidiphyllum trees grow in the margins of valleys and in forests at 650 to 2700 m. Extant Cercidiphyllum, diagnosed on the basis of clustered pod-like fruits and associated elliptical to obcordate, serrate leaves like those of the extant species, occur in the Early Oligocene Bridge Creek flora of Oregon (Meyer & Manchester, 1997). In western North America Cercidiphyllum was present through the Middle Miocene of Idaho and one specimen is known with attached leaves and fruits (Pl. 4 fig. 8 in Smiley & Rember, 1985). In Europe, Cercidiphyllum fruits and leaves extend from the Early Oligocene to Pliocene (Jähnichen et al., 1980; Kvaček & Konzalová, 1996; Kovar-Eder et al., 1998). In Asia, the genus is confirmed by clustered fruits and associated foliage in the Miocene of Korfa, Kamchatka (Chelebaeva, 1971), the Middle Miocene of Hokkaido (Uemura, 1991), and the Middle Pleistocene of central Honshu, Japan (Onoe, 1989). Earlier records of Cercidiphyllaceae from the Cretaceous and Paleocene (which were placed by some authors in the modern genus, Cercidiphyllum) belong to extinct genera, with fruits borne in racemes rather than clusters. The isolated leaves are attributed to the fossil genus Trochodendroides and the fruits have been Nyssidium. In one instance co-occurring leaves of the Trochodendroides kind, inflorescences, and infructescences of the Nyssidium kind, were used along with associated twig architecture and seedlings, to circumscribe a more complete extinct genus, Joffrea (Crane & Stockey, 1985).

2.2.6 Eucommiaceae

Eucommia is native to central China today, with a single species, E. ulmoides, growing at elevations in the range of 200 to 1740 m. The distinctive samaroid fruits (Fig. 26) have an excellent record in the Northern Hemisphere (Takhtajan, 1974; Guo, 2000). The generic determination of these fruits is secure because of the unique morphology and venation, and the presence of latex strands observable in the fossils that correspond in position to the laticifers of extant fruits (Szafer, 1950, 1954; Tralau, 1963; Call & Dilcher, 1997). The laticifers, whose vulcanized rubber tracts often preserve as a reticulum of fine threads partially free from the surface of the fossil compression or imprint, have also been useful to confirm the generic identity of fossil leaves and wood. In North America, the fruits and rarely leaves are known from the Middle and Late Eocene of the western and southeastern United States (Figs. 19, 20; Call & Dilcher, 1997; Manchester, 2000, 2001), and are also well documented from the Oligocene or Miocene of southern Mexico (Fig. 21; Magallon-Puebla & Cevallos-Ferriz, 1994).

Figure 19–26.

Eucommiaceae: Eucommia, fossil and modern fruits. 19.Eucommia montana Brown from Late Eocene Whitecap Knoll, Oregon, USA, UF272–26326. 20.E. eocenica fruit from Bovay clay pit, Holly Springs, Mississippi, UF 15737–8219. 21.E. constans, Puebla, Mexico, UF11054. 22.E. cf. montana from the Early Eocene of Fushun, Liaoning, China, CMPH 53959. 23.E. cf. europaea Mädler from the Pliocene of Auenheim, France, coll. F. Geissert, SMNS P 2096. 24.E. europaea from Mizerna, Poland, KRAMP coll. (Orig. Fig. Szafer 1950, pl. 4, fig. 3). 25.Eucommia fruit from Middle Miocene Shanwang flora, Shandong, China, S2002295. 26. Extant Eucommia ulmoides Oliv. from Lichuan, Hubei, China, PE: G. X. Fu & Z. S. Zhang 1740. Scale bars calibrated in mm.

In Asia, Eucommia is well documented by fruits in the Eocene of Yubari, Hokkaido, Japan (Huzioka, 1961), and Fushun, Liaoning, China (Fig. 22; Geng et al., 1999), the Lower Oligocene of Kiin-Kerish, Kazakhstan (Akhmetiev, 1991), and Kraskino flora from the Khasan Basin, south Primorye, Russia (Ablaev et al., 1993). Several of these occurrences are reviewed in Takhtajan (1974). Eucommia was described and illustrated based on a fruit (Fig. 25) and leaves (Sun et al., 1999) and laticiferous wood from the Miocene Shanwang flora of Shandong Province, eastern China (Wang et al., 2003). Fruits occur at many localities in the Miocene to Pliocene of Japan (Tanai, 1961).

The numerous Eucommia fruit records in Europe extend from the Oligocene to the Pleistocene (Szafer, 1950, 1954; Tralau, 1963; Mai, 1995), including the Miocene of Moldavia (Negru, 1972). Maps showing the modern and fossil distribution were provided by Tralau (1963) and Ferguson et al. (1997). The North American and Chinese Eocene fruits are about 1/3 as large as those of the extant species, and are somewhat more asymmetrical in the placement of stigma at the fruit apex (Call & Dilcher, 1997). As one follows the record of Eucommia fruits through geologic time, a trend of increasing size is obvious, with fruits shorter than 1 cm being prevalent in the Eocene contrasting with larger fruits, e.g., 2.5 cm, in the Miocene. Szafer (1950) pointed out that the Pliocene species, E. europaea Mädler (Figs. 23, 24), has fruits even larger than those of the recent species, E. ulmoides. The former range from 4.4–5.5 cm long (avg. 5.07 cm, n= 22), whereas the latter range from 3.0–4.5 (avg. 3.42 cm, n=67) long. Psilate tricolpate or “incipiently tricol-porate” pollen closely resembling that of the extant genus occurs in the Upper Paleocene of western North America (Pocknall & Nichols, 1996), but the Paleocene leaves attributed to Eucommia by Brown (1962) have been transferred to the unrelated nyssaceous genus Browniea (Manchester & Hickey, 2007).

2.2.7 Eupteleaceae

This family has one genus and two species distributed from northeastern India to central China and Japan. The early fossil record of this family remains in our opinion uncertain, because the distinctive winged fruits have not been recovered, despite the collection of numerous Tertiary lacustrine deposits in the Northern Hemisphere where such fruits would be expected to be preserved. Leaves have been identified to Euptelea from the Eocene and Oligocene of the Pacific Northwestern North America (Wolfe, 1977), but the similarity with leaves of Platanaceae makes it difficult to confirm the identity. Silicified wood of Euptelea was identified based on well preserved silicified secondary xylem from the Middle Eocene of Oregon (Scott & Barghoorn, 1955). Despite some striking similarities between the fossil wood and extant Euptelea, differences in the intervascular pitting and perforations acknowledged by the original authors call for caution in accepting the assignment of this wood to Eupteleaceae (Wheeler & Manchester, 2002). Leaves resembling extant E. polyandra are reported from the Pliocene of central Japan (Ozaki, 1991), but the most reliable record is based on winged fruits and associated leaves from the middle Pleistocene of Shiobara, central Japan (Onoe, 1989).

2.2.8 Hamamelidaceae

This family is widely distributed today, but has several genera confined to eastern Asia (Table 1). Seeds of the Hamamelidoideae subfamily, including Hamamelis, Parottia, and several others have a similar morphology, with a prominent hilar scar and shiny surface related to their dehiscence mode of abrupt ejection from woody capsules. The seeds have converged on very similar morphology related to the constraints of this dispersal mode, and some of the genera might be difficult or impossible to distinguish based on seed morphology alone (Endress, 1989). However, paleobotanists have strained to find characters distinguishing the seeds of this subfamily, and have often made identifications of fossils to extant genera based on configuration of the distinctive hilar scar, overall shape and size (Dorofeev, 1963; Mai, 1987) and course of the raphe impressed on the inside of the seedcoat (Manchester, 1994). Except for some detailed studies of Corylopsis seeds in relation to those of other Hamamelidoideae (Zhao & Li, 2008), there has still not been a detailed comparative treatment of all of the genera to show that they can be truly distinguished, so there may be some question remaining about the validity of some of the determinations of Disanthus, Loropetalum, Fortunearia, Eustigma, Sinowilsonia, Distylium, Sycopsis, Hamamelis, and Fothergilla.

Corylopsis ranges from the Himalayas to Japan today with about 30 species, including 20 in southwestern and southeastern China. It was formerly distributed in Europe and North America. The global fossil record of the genus, with occurrences in North America, and Europe as well as Asia, was reviewed by Zhao and Li (2008). The oldest known record is the species C. venablesi Chandler based on seeds with a basilateral hilar scar 1/2 to 1/4 the length of the seed one side and a facet on the opposite side, from the Early Eocene of London Clay flora of southern England (Chandler, 1961). Grote (1989) recognized Corylopsis on the basis of seeds from the Middle Eocene of Tennessee (e.g., Fig. 27). He noted that a distinctive asymmetrical hilar scar facilitates the discrimination of Corylopsis seeds from seeds of other extant genera of the Hamamelidoideae. Leaves of Corylopsis were recognized from the Eocene of Republic, Washington, USA by Radtke et al. (2005) and from the Oligocene of western Japan (Hori, 1987; Uemura et al., 1999). Zhao and Li (2008) identified well-preserved seeds of Corylopsis from beds of probable Miocene age in southwestern Yunnan, China. In addition, they provided a table with characters distinguishing seeds of some other extant genera of Hamamelidoideae. According to their analysis, there are two distinct scars in Sinowilsonia, Distylium and Corylopsis, one on each side near the base but not united over it. The Corylopsis seeds can be distinguished by a narrow sunken asymmetric hilar scar on one side and a marked facet on the other.

Figure 27–33.

27. Hamamelidaceae. Seed of Corylopsis sp. from the Eocene of Tennessee, USA, viewed ventrally and dorsally with hilar scar oriented to the left, det. P. Grote, UF 15803–9115. Scale bar calibrated in mm. 28–30. Juglandaceae: Extant and fossil Cyclocarya.28. Extant Cyclocarya paliurus, A: S. C. Sun 1296, Anhui, China, UF Ref. coll. 4000. 29.C. brownii Manchester & Dilcher from the Paleocene of North Dakota, USA, UF 15722–4039. 30. Detail of nutlet in 29, with base of nutshell abraded to reveal 4-lobes of the base of locule, and orthogonal intersection of primary and secondary septa. Scale bars calibrated in mm. 31–33. Mastixiaceae: Fruits of Recent and fossil Diplopanax in transverse section. 31. Extant Diplopanax stachyanthus Vinh Phu (Tam Dao II), northern Vietnam, Nguyen Tien Ban 121; Komarov Inst., St Petersburg. 32.Tectocarya rhenana from Düren, Germany, Staatliche Museum für Naturkunde in Stuttgart s.n. 33.Diplopanax sp. from Late Eocene Quimper Sandstone, Oak Bay, Jefferson Co., Washington, USA, coll. J. Goedert 1988, UWBM 36892. All at same magnification (scale bar=1 cm).

Disanthus is another genus of Hamamelidoideae with one extant species now confined to eastern China and Japan. In Germany, D. bavaricus was recognized from Oligo-Miocene of Schwandorf (Gregor, 1977), and from Early Oligocene Haselbach series (Mai & Walther, 1978). Knobloch and Mai (1986) recognized hamameli-daceous seeds with the distinctive hilar scars from the Late Cretaceous of Austria and Germany and named them to extant Disanthus, but without detailed justification regarding the generic assignment. Disanthus austriacus was described as an exceptionally small-seeded species from the Campanian-Maastrichtian of Sievering, Austria and D. hercynicus was described based on larger, multifaceted seeds from the Maastrichtian of Eisleben (Knobloch & Mai, 1986). An additional species was named from the Paleocene of Germany (Mai, 1987). Until a more thorough morphological and anatomical comparative treatment of extant and fossil seeds is conducted, we consider these geologically older records to be provisional.

Fortunearia is a genus of shrubs distributed in central and eastern China. Dorofeev (1963) identified seeds similar to those of extant F. sinensis from near the River Tym of western Siberia. A fossil seed species named F. altenburgensis Mai occurs in the middle to Lower Oligocene of Haselbach Series, Germany (Mai & Walther, 1978), but the justification for placement in this genus was not presented. Subsequently, Mai (1998) recognized the same species from the middle Oligocene Calau beds in Brandenburg, Germany, but he indicated that the seeds “either belong to a Fortunearia or Sinowilsonia species with small seeds”. The genus has been identified in Japan on the basis of Pliocene leaves (Ozaki, 1984) and seeds (Miki, 1941). Infructescences of the fossil genus Fortunearites from the Eocene of Oregon bear seeds with a combination of characters found today only in the Asian endemic sister genera Fortunearia and Sinowilsonia (Manchester, 1994).

2.2.9 Hydrangeaceae

Schizophragma is a genus of woody climbers extending from the Himalayas through Japan, with 11 species, 9 of which occur in China, ranging from 200 to 2900 m in elevation. It has capsular fruits, with united styles terminating in a large capitate stigma; the capsule dehisces by decay of intercostal tissue. Schizophragma is recognized based on immature fruits from the Pliocene Kroscienko flora of southern Poland by Mai (1985) and is known from well preserved fruiting heads in the Pliocene of northern Italy (Martinetto, 2001a). In Japan, fossil leaves closely similar to those of extant S. hydrangeoides were identified from the Pliocene Kabutoiwa Formation of Central Honshu (Ozaki, 1991). Also, a leaf attributed to the modern species S. hydrangeoides was described from the middle Pleistocene of Shiobara, central Honshu (Onoe, 1989).

Although Hydrangea is geographically widespread with numerous species in the Northern Hemisphere, and extends into South America, H. anomala constitutes a distinct clade called subsection Calyptranthe by McClintock (1957) which is confined to eastern Asia (Eastern Himalaya, central China, Korea, Japan). This is the only species of Hydrangea with seeds having an encircling wing. Silicified Hydrangea fruits containing winged seeds indistinguishable from those of H. anomala were described from the Eocene of western North America (Manchester, 1994).

2.2.10 Juglandaceae

The Juglandaceae include two genera endemic to eastern Asia: Cyclocarya and Platycarya. Pterocarya is also mostly eastern Asian in distribution, but with an additional species living in the Caucasus region. Although pollen and leaflets may be readily recognized to this family and subclades, the generic distinctions are based primarily on fruit characters. Because of overlapping foliar and pollen morphological characters among the extant genera as well as with some extinct genera of the family, we confine our attention to records confirmed on the basis of fossil fruits.

Cyclocarya is distributed today in southern, central and north-central China (Iljinskaya, 1953; Manning, 1975; Ying et al., 1993). It has distinctive fruits consisting of a small nutlet, surrounded by a prominent, circular disk-like wing with radiating dichotomous venation (Fig. 28). Care must be taken, however, to distinguish Cyclocarya fruits from morphologically convergent fruits Paliurus (Rhamnaceae), which also has a widespread Tertiary fossil record (Burge & Manchester, 2008), and Dioncophyllum (Dioncophyllaceae). Although Cyclocarya is most easily identified when both the wing and the nut are preserved (Iljinskaya, 1994), it is also possible to recognize based on the morphology of isolated nuts (Dorofeev, 1970, 2004). Cyclocarya fruits are common in the Paleocene of the North American Great Plains region (Figs. 29, 30; Manchester & Dilcher, 1982; Manchester, 1987), extending to the Early Eocene (Burge & Manchester, 2008). Cyclocarya ranges from the Oligocene to Upper Pliocene in Europe and Asia (Manchester, 1987; Iljinskaya, 1994), with the Asian records from western Siberia (Dorofeev, 1970), Kazakhstan and Primorye (Iljinskaya, 1994) and Japan (Miki, 1955; Ozaki, 1991). Isolated nutlets with wings absent and apparently abraded away, called Juglandicarya depressa Chandler, common in the Early Eocene London Clay flora of England, show internal structure consistent with that of Cyclocarya. A Paleocene fruit impression from northeastern China was described as C. macroptera by Tao and Xiong (1986), but it corresponds rather to the circular-winged fruit of the Dioncophyllaceae (Dioncophyllites amurensis Fedotov) recently recognized from the Eocene Raitschicha flora of the Amur region, southeastern Russia (Budantsev, 2005, p. 30, pl. 4). A juglandaceous locule cast with four basal lobes indicating development of the secondary as well as primary septum, was described as Platycarya cordiformisMai (1987) from the Lower Paleocene of Gonna; however, the cast matches more closely those of Cyclocarya.

Platycarya has three species of deciduous trees distributed in China, Vietnam, Korea and Japan at elevations of 500–1300 m. The modern species typically have imparipinnately compound leaves, but P. simplicifolia has simple leaves. The fruits are bi-winged nuts borne in globose to elongate-ellipsoidal cone-like infructescences. Infructescences with intact fruits are known from the Early Eocene of England (Reid & Chandler, 1933 as Petrophylloides; Manchester, 1987) and North Dakota (Wing & Hickey, 1984). The extinct fruit genera Hooleya from the Eocene of North America (Manchester, 1987; Wing & Hickey, 1984) and the Eocene to Oligocene of Europe (Reid & Chandler, 1926; Rasky, 1956) and Paleoplatycarya from Paleocene of North America show affinities with Platycarya (Wing & Hickey, 1984; Manchester, 1987). The triporate pollen of Platycarya has the usual diagnostic features of Juglandaceae (porate with ornamentation of evenly distributed scabrae) but is distinctive among other extant juglandaceous pollen by the presence of pseudocolpi, a pair of thin oblique troughs in the exine on both polar hemispheres. The same kind of pollen co-occurs with the extinct fruit genera, indicating that such pollen is diagnostic of the tribe, but not to genus, when the Tertiary record is considered. Hence, the fossil genus name Platycaryapollenites Nagy is preferred for fossil pollen grains. Platycaryapollenites has been reported from the Eocene of North China sea (Song et al., 1999, 2004), as well as from Paleogene of North America and Europe. Despite the occurrence of juglandaceous leaflets assigned by some authors to Platycarya, the diagnostic infructescences of Platycarya have not been found in the Asian Tertiary.

2.2.11 Lardizabalaceae

This family is disjunct today between South America and Asia, but most of the genera are endemic to eastern Asia: Akebia, Decaisnea, Holboellia, Sargentodoxa, Sinofranchetia, and Stauntonia.

Akebia has five species living today in eastern Asia. Mai (2001a) identified seeds of Akebia, A. parvisemina Mai, from the Upper Miocene of the Bröthen clay pit. He indicated that the fossils correspond in morphology to the seeds of all three extant species of Akebia, but anatomical details were not presented, and diagnostic features for seeds of Akebia, which would allow them to be distinguished from seeds of all other angiosperm genera, were not mentioned. Therefore, these fossils are in need of more detailed comparative work to confirm their identity.

Decaisnea has two extant species in the eastern Himalayan region and central China. The fruits of this genus are leathery follicles with seeds mainly in two rows surrounded by white pulp. The seeds of this genus are laterally compressed, and obovoid to oblong in outline with a thin testa consisting of an outer layer of isodiametric cells and an inner layer of radially elongate cells. In contrast to other genera of the family, it lacks a prominent hilar marking. Mai (1980) recognized a fossil species based on seeds from the Lower Miocene of Borna-Ost, near Leipzig, Germany, D. bornensis Mai. The fossil species corresponds to the extant genus in morphology, including placement and size of the hilum, raphe and micropylar point and in anatomy of the seed coat. According to Mai, the fossil seeds of D. bornensis deviate from extant D. fargesii Franch. seeds by having smaller width in relation to length and the more distinctly inclined, subapical chalazal region, supporting separate species status.

Sargentodoxa is a genus of two species of deciduous lianas ranging from south-central to eastern China to northern Laos. It grows in forests and in thickets at forest margins, usually climbing on other vegetation, in soils with a pH from 4.5 to 6.0, at elevations of (130–)400–1900(–2400) m. The leaves are estipulate and simple to digitately trifoliolate with entire-margins. Sargentodoxa has distinctive shiny seeds with a rounded base and slightly oblique apical truncation, described in detail by Tiffney (1993). In North America the fossil seeds are known from the Middle Eocene of Oregon (Manchester, 1999), the Early Miocene Brandon lignite of Vermont (Tiffney, 1993), and the late Miocene or Pliocene Gray site in Tennessee (Yu-Sheng Liu, pers. comm., 2007). Seeds of S. lusatica (Mai) Mai have been recognized from the Late Eocene to Late Oligocene of northwest Saxony and Middle Miocene of Lausitz, Germany (Mai, 2001a). Well-preserved Sargentodoxa seeds have also been found in the uppermost Miocene-Lower Pliocene dredging flora of Alsace and the Pliocene of Italy (Martinetto, 2001b).

2.2.12 Malvaceae

This family (incl. Tiliaceae, Sterculiaceae, Bombacaceae as well as traditional Malvaceae—Bayer & Kubitzki, 2003) is widespread particularly in the tropics today, but has only a few genera endemic to eastern Asia.

Extant Craigia, traditionally placed in the Tiliaceae, has two species: C. yunnanensis W. W. Smith & W. E. Evans of southern China (Guangxi, Guizhou, Yunnan, southeastern Xizang), and northern Vietnam, and C. kwangsiensis Hsue of Guangdong Province, China. It grows in broadleaved evergreen and deciduous mixed forests and seasonally wet forests in limestone areas, in soils with a pH ranging from 6.0 to 7.5 at elevations of 1400–1700 m. The genus was widely distributed through the Tertiary (its fruits were formerly considered to be an extinct genus, Pteleaecarpum; Bůžek et al., 1989). With the recognition that the fossil fruits represent Craigia (Kvaček et al., 1991), it has been possible to document an extensive history of this genus throughout the Northern Hemisphere with many fruit records in western North America, Europe, and Asia (Kvaček et al., 2005). The distinctive fruit valves are known from the Late Eocene or Early Oligocene of Spitsbergen and the Middle Eocene to Early Oligocene of Western North America, but in Europe, the fruit records extend from the Oligocene to the Pliocene. In Asia, Craigia fruits have the greatest stratigraphic range, from the Paleocene in Kamchatka to the Late Miocene of Sikhote-Alin (Kvaček et al., 2005).

The genus Reevesia Lindley, originally based on the species distributed from the eastern Himalaya to Taiwan and Yunnan, has been recognized by some authors to include the central American genus Veeresia. The status of Reevesia as a genus endemic to eastern Asia depends, however, on whether Veeresia is treated as a distinct entity or not. If V. clarkii Monach. & Moldenke of southern Mexico is a treated as an American representative of Reevesia, the genus would be considered disjunct between the two continents, rather than endemic to eastern Asia (Mabberley, 1997). Reevesia has been recognized in the Tertiary of Europe based on pollen (Reevesiapollis Krutzsch) corroborated by both light and scanning electron microscopy from the Lower Miocene of Oberdorf, Austria (Meller et al., 1999) and by an association of leaves, fruit valves and winged seeds from the Miocene of Bilina, Czech Republic (Kvaček, 2006). Woods anatomically similar to Reevesia are known from the Paleogene and Miocene of Japan (Terada & Suzuki, 1998).

2.2.13 Mastixiaceae

Diplopanax, with two extant species, is distributed in China (Guangxi, Guangdong, Hunan, Yunnan), Vietnam and Cambodia. Although this tree was originally thought to belong to the Araliaceae, fruit morphology, and molecular sequence data indicate that it belongs within the Cornales as a sister to Mastixia (Eyde & Xiang, 1990; Fan & Xiang, 2003) in the Mastixiaceae clade. Diplopanax fruits are easily recognized by their ellipsoidal woody fruits with a single-seeded boat shaped locule and elongate germination valve. In transverse section, the fruits are circular with a C-shaped locule (Fig. 31). Diplopanax fruits are similar to those of Mastixia, but have numerous scattered vascular bundles rather than a single pair of ovular bundles. The margins of the germination valve are perpendicular to, rather than tangential to the limbs of the locule. In Europe, most of the fruits attributed to Mastixicarpum (a fossil fruit genus established before Diplopanax was known) probably also belong to Diplopanax (Eyde & Xiang, 1990; Czaja, 2003; Ševčík et al., 2007), indicating a stratigraphic range from Early Eocene to Miocene. The fossil genus Tectocarya (Fig. 32) is also very similar to, and likely congeneric with, Diplopanax. Diplopanax has been recognized based on fruits from the Middle and Late Eocene of Oregon (as Mastixicarpum, Manchester, 1994; Tiffney & Haggard, 1996; Manchester & McIntosh, 2007) and the Middle Eocene of British Colombia, Canada (Stockey et al., 1998). An additional occurrence from the Late Eocene of Washington recently came to light (Fig. 33). As yet, neither Diplopanax nor Mastixia has been recognized in the Asian fossil record.

2.2.14 Menispermaceae

This family is well distributed in tropical regions today, but has only one genus that is endemic to eastern Asia: Sinomenium which has one extant species in central China and Japan. Cyclea extends from China to the Philippines, and hence exceeds our area of emphasis, but also has fossil records in Europe (Martinetto, 2001a, b). Diploclisia extends into Malesia as well as China, and has Eocene fossil occurrences in North America (Manchester, 1994). These genera, like most in the family, are readily recognizable based on endocarp morphology. Sinomenium endocarps were first recognized in the European Tertiary based on endocarps from the Pliocene of Poland (Szafer, 1947) and are now known from several more occurrences in the Miocene of Europe, as reviewed by Kirchheimer (1957), and in the Pliocene of Italy (Martinetto, 1998). Dorofeev (1963) recognized the species S. cantalense (E. M. Reid) Dorof. based on fruits from the Pliocene of Pont-de-Gail, France, the Kroscienka flora of Poland, and from western Siberia. Another species, S. militzeriKirchheimer (1957) has endocarps that are also close to extant S. acutum and to the fossil S. cantalense, but differs from both of these species by having higher protuberances of the external and lateral crests. Mai (1997) considers that characteristics of the endocarps of the Eocene fossil genera Palaeosinomenium Chandler, and Wardensheppeya Eyde (=Wardenia Chandler) differ only in specific, rather than generic characters, from Sinomenium. He therefore considers that Sinomenium extends from the Eocene to the Pliocene of Europe. Palaeosinomenium endocarps were also recognized from the Middle Eocene of Oregon, USA (Manchester, 1994) and Huadian, Jilin, China (Manchester et al., 2005).

2.2.15 Nymphaeaceae

Euryale is the only member of the water lily family confined to eastern Asia. The distinctive seeds of Euryale facilitate recognition and distinction of paleobotanical records. While many other genera of the family have excellent fossil records, the fossil record of extant Euryale has proven elusive. Euryale nodulosa seeds from the Pliocene of Netherlands and Italy are similar to those of living E. ferox in macroscopic shape and general structure, “but with shorter and broader elliptic embryotega, finer cell sculpture and more prominent nodules on the external surface. In addition, they show a different testa structure in cross section” (Martinetto, 2001b, p. 156). This species could alternatively fit the diagnosis for the form genus Paleoeuryale Dorofeev. Seeds assigned to an extinct genus, Susiea from the Paleocene of North America, appear to have their closest similarity to Euryale among extant genera. Susiea differs, however, by having rectangular, rather than polygonal, epidermal cells and in the thickness of the seed coat and raphe morphology (Taylor et al., 2006). Miki (1960) described 4 species of Euryale based on seed remains at many localities of the Pliocene and Pleistocene of Japan. Three species were identified to European fossil species (E. europaea Weber, E. lissa Reid, E. nodulosa Reid), and one to the modern species, E. ferox.

2.2.16 Nyssaceae

This family includes the extant genera Nyssa, Camptotheca, and Davidia, plus the extinct genera Amersinia and Browniea (Manchester & Hickey, 2007).

Davidia has one species, D. involucrata, native to the broad-leaved forests or evergreen forests, at altitudes of 1100–2600 m in southwest and west Hubei Province, China. It has a distinctive ellipsoidal fruit with a woody stone containing several single-seeded locules, each with an elongate dorsal germination valve. An extinct species, Davidia antiqua (Newberry) Manchester, was common in the Paleocene of North America, based on well preserved leaves and fruits from the Paleocene of Wyoming, Montana and North Dakota (Manchester, 2002). Similar leaves and fruits occur in the Paleocene of southeastern Russia (Manchester, 2002). In North America, silicified fruits indicate that the genus survived at least to the Late Eocene in Oregon (Manchester & McIntosh, 2007). Leaves virtually indistinguishable from those of extant Davidia were described as a fossil genus, Tsukada, from the Middle Eocene of Republic, Washington (Wolfe & Wehr, 1987). No occurrences of Davidia have been found in the paleobotanical record of Europe despite conditions favorable for the preservation of woody fruits. In Japan, Davidia fruits and leaves indistinguishable from the modern Chinese species occur in the Pliocene of central Honshu (Kokawa, 1965; Ozaki, 1984; Tsukagoshi et al., 1997). The extinct fruit genus Amersinia combines characters of Camptotheca and Davidia. Along with the associated foliage, Beringiaphyllum, these fruits were widespread in the Paleocene of eastern Asia and North America (Manchester et al., 1999).

Wood conforming anatomically to Camptotheca was described from the Oligocene of Tsuyazaki, northern Kyushu, Japan (Suzuki, 1975), but the wood is also anatomically similar to other genera. The distinctive fruits of Camptotheca have not been found in the fossil record. The extinct Paleocene genus Browniea has infructescences and fruits similar to those of Camptotheca, but Browniea had fruits with persistent perianth lobes not present in the extant genus, as well as different foliage and pollen (Manchester & Hickey, 2007).

2.2.17 Rhamnaceae

Hovenia is a genus of deciduous trees and shrubs with five species ranging from the Himalayas to Japan; in southwest to eastern China it occurs at altitudes of 200 to 2100 m. The leaves are distinctive in their ovate outline, serrate margin with small glandular teeth, asymmetrical base and peculiar venation in which the lower margin of the lamina is delimited by the lowermost pair of secondary veins (Figs. 34–36). Fossil leaves occur in the Oligocene of Oregon, USA (Figs. 35, 38; Meyer & Manchester, 1997), and the Middle Miocene Shanwang flora of Shandong Province, China (Fig. 36; Hu & Chaney, 1940; Sun et al., 1999). Wood conforming anatomically to Hovenia has been described from the Oligocene of northern Kyushu (Suzuki, 1982) and Lower Miocene of southwestern Honshu (Watari, 1952), Japan. We exclude from the genus, leaves described as H. cuneiformis from the Paleogene of South Primorye (Ablaev, 2000) because they do not show the base of the lamina outlined by the basal pair of secondary veins—an important feature of Hovenia and a few other genera of Rhamnaceae. From the prominence of glandular teeth and transverse arrangement of tertiary veins, the species appears instead to represent the Salicaceae.

Figure 34–41.

34–38. Rhamnaceae: Hovenia, fossil and Recent leaves. 34. Extant Hovenia acerba Lindl., Fenye Co., Kiangsi, A: K. Yao & K. Yao 9109. 35. H. oregonensis Meyer & Manch. Early Oligocene Bridge Creek flora, Oregon, UF 243–10731. 36.H. miodulcis Hu & Chaney, Middle Miocene Shanwang flora, Shandong, China. S100197. 37. Enlargement from 34. 38. Enlargement from 35. Scale bars 3 cm in figs. 34–36. 39–41. Sapindaceae: Recent and fossil fruits of Dipteronia. Scale bars calibrated in mm. 39. Extant schizocarp of D. sinensis with two fully developed mericarps, A: B. Bartholomew et al., 1063, Hubei, China. 40.Dipteronia brownii McClain & Manch. from Early Eocene of McAbee, British Colombia, UWBM 97675. 41. Mericarp of Dipteronia sp. from the Paleocene of Archara Bogochan coal mine, Zeya Bureya basin, GINRAS ab 5–11.

2.2.18 Rubiaceae

Emmenopterys has one extant species, E. henryi, native to western to eastern China. It grows in broadleaved evergreen and mixed broadleaved evergreen and deciduous forest with pH 5–6, at elevations of 700 to 1300 m but usually 300 m in southeastern China and 1600 m in south-central China. This genus belongs to the tribe Cinchoneae which is characterized by elongate bilocular capsules with winged seeds and axile placentation (Andersson & Persson, 1991). Emmenopterys dilcheri, from the Eocene of Oregon based on well preserved infructescences containing anatomically preserved winged seeds, corresponds closely to extant E. henryi in infructescence branching pattern, inferior ovary, elongate bilocular fruits, axial placentation, and the morphology a pattern of reticulate thickening on the seed coat cells of the winged seeds (Manchester, 1994). A similar infructescence was also illustrated from the Middle Eocene of Eckfeld, Eifel, Germany (Pl. V, fig. 10 in Wilde & Frankenhäuser, 1998), but a broader study of the fruits and seeds of extant Cinchoneae is needed to ascertain its position.

2.2.19 Rutaceae

The Tertiary record of Europe and North America includes many occurrences of rutaceous seeds as has been reviewed by Tiffney (1980) and Gregor (1989). Some of these genera are widely distributed today in warm regions, e.g., Zanthoxylum and Toddalia, but Phellodendron is limited to eastern Asia including far eastern Russia, China, Korea, and Japan (Tiffney, 1980). Although some members of the family are easily recognized based on seed morphology, several extant genera are similar and perhaps overlapping in seed morphological characters. The form genus Rutaspermum has thus been applied to some of the fossil species. Nevertheless, extant Phellodendron seeds are sufficiently distinctive that it has been possible to recognize fossil seeds with some confidence. This genus is confined to eastern Asia today with about 10 species. Fossil seeds of Phellodendron have been identified from the Neogene of Europe and Asia, and the Miocene Brandon Lignite (Tiffney, 1980). Tiffney (1981) challenged the prior identification of Phellodendron from the Eocene of southern England, observing characters supporting reassignment of those fossils to Euodia, but in the same investigation he accepted the other European records of the Phellodendron from the review of Kirchheimer (1957). Tralau (1963) provided a map and review of the numerous European records of Phellodendron seeds, extending from the Oligocene to Pliocene. The seeds are found to the end of the Pliocene in central Europe and to the Early Pleistocene in Italy (Martinetto, 1998). Leaves reported as Phellodendron from China and Russia are in our opinion questionable.

2.2.20 Salicaceae

Idesia is a genus now endemic to China, Korea and Japan. Its fruits are berries, unlike the capsules characteristic of related Populus and Poliothyrsis. Idesia is identified based on leaves with well-preserved venation from the northern California Weaverville flora (MacGinitie, 1937) of probable Early Miocene age (Barnett, 1989). Idesia leaves are similar to Populus in glandular teeth, but the laminae have truly palmate primary venation, without decurrence of lateral primaries along the midvein. According to MacGinitie, every character of the fossil leaves of I. cordata MacGinitie is matched in the leaves of extant I. poly-carpa Maxim. If correctly determined, this western North American fossil speies indicates that this genus, now endemic to China, crossed between Asia and North America sometime during the Tertiary. In Asia, the genus has been identified by leaf impressions from the Paleocene to Lower Eocene of Andyrka, Kiin Kerish (Iljinskaya in Budantsev, 2005; Chelebaeva in Budantsev, 2005).

2.2.21 Sapindaceae

Dipteronia, the sister genus of Acer, has two extant species endemic to China with distinctive schizocarpic winged fruits (Fig. 39). This genus has an excellent fossil fruit record in North America, beginning in the Late Paleocene and continuing through the Early Oligocene (McClain & Manchester, 2001). Several complete fruit specimens from the Middle Eocene of Oregon, Washington, and British Columbia show that the mericarps were commonly borne in schizocarps of three (a typical feature of Sapindaceae) as well as in pairs (e.g., Fig. 40), in contrast to the modern species which usually have only paired mericarps. Dipteronia has not been observed in the Tertiary of Europe, despite the excellent record there of Acer and other kinds of winged fruits. The fossil record of Dipteronia in Asia is not well known. A figured Dipteronia fruit specimen reported to have come from the Eocene of Fushun, Liaoning, China (Manchester, 1999) was later discredited as being a misplaced museum specimen actually from the Eocene of western Canada (McClain & Manchester, 2001). However, a mericarp was subsequently discovered during fieldwork by Akhmetiev and Manchester from the Paleocene Tsagayan Formation of Amur region, southeastern Russia (Fig. 41; Akhmetiev et al., 2002), confirming an early presence of the genus in Asia.

Koelreuteria, with three extant species, is native today in China. Although one species is also found disjunct to Fiji, we have included the genus in this treatment as being “almost” endemic to east Asia. The genus has a good fossil record in North America, Europe and Asia, especially supported by the distinctive fruit remains (Fig. 11 in Manchester, 1999). Koelreuteria fruits are inflated, bladder-like capsules with reticulate venation. The seeds are attached on an incomplete septum 1/3 to 1/2 of the fruit length from the base. The oldest North American examples are from the Middle Eocene of the Green River Formation (Fig. 11 A in Manchester, 1999) and there are impressive examples from the Late Eocene Florissant Formation (MacGinitie, 1953, 1969). In Europe the oldest known examples are from the Oligocene of Rott, Germany (Weyland, 1937), extending to the Miocene of Randecker Maar, Germany (Rüffle, 1963), and Bohemia (Bůžek, 1971). In Asia, the fruit valves have been recognized from the Middle Eocene of Huadian in southern Jilin Province, China (Manchester et al., 2005), from the Paleogene of southern Primorye (Ablaev, 2000), as well as from the Miocene Shanwang flora of Shandong Province, China (Hu & Chaney, 1940) and Late Miocene Tatsumitoge flora of southwestern Honshu, Japan (Ozaki, 1980). In some instances fruit valves of Craigia (=Pteleaecarpum) have been mistaken for Koelreuteria, but they can be distinguished by the serial attachment of seeds, the complete septum and more elongated areoles in the fruit valve venation. Koelreuteria has an incomplete septum with seeds borne at a single level within the pod.

Sinoradlkofera F. Meyer (syn. Boniodendron), with one species in China and Vietnam is a segregate from Koelreuteria Laxm. that differs by its paripinnate leaves, regular flowers, and the absence of an androgynophore (Meyer, 1976; Buijsen et al., 2003). In addition, mature capsules of S. minor are about half the size of those in Koelreuteria species. Some of the fossil fruits previously assigned to Koelreuteria conform more closely to Sinoradlkofera, and might represent that genus, although more detailed comparative work is needed. These include Koelreuteria arnoldii Becker from the Oligocene of Ruby, Montana (Becker, 1961), and Republic, Washington (Wolfe & Wehr, 1987).

2.2.22 Scrophulariaceae

Although most members of this family are herbaceous, Paulownia is a species of trees native to eastern Asia. It has large, distinctive bivalved loculicidally dehiscent capsules and tiny winged seeds. Fossil representatives have been confirmed by sedimentary casts of the characteristic fruit valves from the Middle Miocene of Bavaria, Germany (Butzmann & Fischer, 1997). In addition, isolated winged seeds are known from Early and Middle Pliocene sites in northern Italy (Martinetto, 1998). Seeds denuded of the wing have been identified to P. cantalensis (Reid) Mai from the Pliocene of Cantal, France, to Lower Miocene of the Lausitz region (Mai, 2001a). Watari (1948, 1952) described wood conforming anatomically to Paulownia from the Lower Miocene of southwestern Honshu, Japan.

2.2.23 Staphyleaceae

This family includes the genera Euscaphis, Staphylea, and Turpinia. Simmons (2006) prefers to sink Euscaphis and Turpinia within Staphylea based on inferences from molecular data, but these genera are distinguished morphologically by their fruit types which are baccate in Turpinia, bladder-like in Staphylea, and dehiscent follicles in Euscaphis. The spherical shape and small hilum of the seed distinguishes Euscaphis from seeds of the other two genera (Tiffney, 1979). Euscaphis has one extant species endemic to eastern Asia. The seed is lenticular in form because it lacks any pressure marks from adjacent seeds (a distinction from Turpinia which bears multiple seeds per fruit that crowd each other in development) and has a thin shiny sarcotesta and a large hilum with 5 vascular bundle scars, but not with the surrounding bulge seen in Staphylea seeds (Mai, 1980). Fossil seeds conforming to Euscaphis have been identified based on morphology and seed coat anatomy from the middle Oligocene of Nerchau, Saxony, Germany (Mai, 1980). In Asia, the seeds are known from the Pliocene of Yahata, Iki, Kyushu, Japan (Miki & Kokawa, 1962). In older classifications, Tapiscia was placed in the Staphyleaceae, but it is now treated in a separate family (see Tapisciaceae, below).

2.2.24 Styracaceae

Rehderodendron is related to Halesia, but has unwinged, buoyant fruits (Figs. 42, 43). The fruits are 2–3 locular with prominent lacunae radiating from the central area (Fig. 44). The genus includes four species of deciduous shrubs and trees distributed in southwestern China (Yunnan, Guizhou, Sichuan, Guangxi, Guangdong and Hunan) and Vietnam, occurring in dense forests at elevations from 100–1500 m. The genus is confirmed by well preserved fruits from the Tertiary of Europe, including the Early Eocene London Clay of England (Figs. 50, 51; Mai, 1970), the Miocene of Germany (Figs. 45–49; Mai, 1970), the Pliocene of Germany and Italy (Geissert & Gregor, 1981; Martinetto, 1998), and the Upper Pliocene of Romania (Mai & Petrescu, 1983). A morphological key to the fossil species was provided by Mai and Petrescu (1983). Melliodendron was recognized based on degraded fruits from the Plio-Pleistocene of Japan (Miki, 1968), however the illustrated specimens show radiating longitudinal blades of sclerified tissue coinciding with Rehderodendron rather than Melliodendron. Transverse sections of the fruit would be required to verify the assignment to Melliodendron.

Figure 42–55.

42–51. Styracaceae: Recent and fossil fruits of Rehderodendron. Scale bars calibrated in mm. 42, 43. Lateral and apical view of fruit of extant Rehderodendron sp. from N Burma, BM: F. Kingdon-Ward 22086. 44. Transverse section of extant Rehderodendron macrocarpus Hu, Sichuan, China, PE 55291: T. U. Tu 730 showing three locules and radiating blades of endocarp tissue with and intervening lacunae. 45–49.R. ehrenbergii (Kirchheimer) Mai from Mine Alfred, Düren, Germany, coll. Claire A. Brown 1952. 45, 46. Fruit in lateral and apical view, USNM 537358. 47, 48. Fruit in lateral view and in transverse section, showing two well developed locules. USNM 537359. 49. Transverse section of the specimen in 46, showing three well developed locules. 50, 51.R. stonei (Reid & Chandler) Mai from the Early Eocene London Clay. 50. Lateral view showing meridional ribs and apical protuberance, BM v30451, Herne Bay, England. 51. Specimen in transverse section showing one well developed locule and an axial canal, BM v30347. 52–55. Toricelliaceae: Fruits of extant and Paleocene Toricellia. All at same magnification (scale bar=1 mm). 52.Toricellia tiliaefolia, transverse section of fruit, showing three chambers: two large and empty, one smaller and containing a seed, Yunnan, China, MO 52556: A Henri 11907. 53–55.Toricellia bonesii (Manch.) Manch., permineralized fruit in front, lateral, and transversely sectioned views, Late Paleocene of Almont, North Dakota, USA, FMNH pp22421.

Pterostyrax is native in eastern Asia from Burma to Japan. Mai (1998) recognized fossil fruits of Pterostyrax from the Oligocene Calau beds of Brandenburg, Germany, and called attention to another species, P. europaeaZablocki (1930). Mai stated that the fossils display a ring of calyx lobes surrounding an obtuse stylar cone and an almost inferior drupe. These typical characteristics place the fossils unequivocally in the genus Pterostyrax Sieb. & Zucc.” A twig with attached fruits and leaves of this genus was illustrated and described from the middle Pleistocene of Shiobara, central Honshu, Japan (Onoe, 1989).

2.2.25 Tapisciaceae

Tapiscia is a monotypic genus of deciduous trees with odd-pinnately compound estipulate leaves distributed across southern and southeastern China south of Yellow River, and northernmost Vietnam. It occurs today in the mixed mesophytic forests of China, in soils with pH 4.5 to 5.5 at elevations of 720–2550 m. Although formerly placed in the Staphyleaceae, molecular and morphological studies indicate that Tapiscia, and the neotropical genus Huertea, form an unrelated family (Soltis et al., 2005). Huertea and Tapiscia share distinctive subglobose seeds with a prominent concave chalaza, rounded base and pointed micropylar end, but those of Huertea are larger and less sharply pointed (Manchester, 1988). Tapiscia seeds are known as fossils from the Eocene of England, Germany (Mai, 1980), and in western North America (Oregon: Manchester, 1988, 1994). Reports of the genus based on foliage from the Miocene Shanwang flora (WGCPC, 1978) and from the Paleocene of Canada (Chandrasekharam, 1974) are unconvincing. The latter record was reassigned to the extinct nyssa-ceous genus BrownieaManchester & Hickey (2007).

2.2.26 Toricelliaceae

Toricellia is a genus of small trees with three species distributed in northern India and southwestern China. The fruits, like those of the related Madagascan genus Melanophylla, are distinguished by endocarps of three chambers: a small central chamber containing a seed, and two large lateral chambers that are empty; there is no central vascular strand, and the endocarp wall and septa are composed of isodiametric sclereids (Fig. 52; Manchester, 1999; Meller, 2006). Fossil endocarps of Toricellia are known from the Eocene of Oregon and Washington, USA (Manchester, 1999), as well as from the Eocene of Messel, Germany and the Miocene of Oberdorf, Austria (Meller, 2006). The oldest known occurrence is from the Paleocene of Almont, North Dakota, USA, based on the single specimen illustrated here (Figs. 53–55).

2.2.27 Trapellaceae

The genus Trapella includes aquatic perennial herbs distributed in eastern Asia. The distinctive spiny fruits of Trapella are recognized in the Pliocene of western Germany (Tralau, 1964, 1965) and the Miocene of Siberia (Dorofeev, 1963). Another occurrence is known from the Late Miocene of Hungary (Bůžek unpublished, Mai, 1995). Fruits of Trapella, including three extinct species, plus examples of the extant species, T. sinensis Oliv., were also recorded from the Pliocene and Pleistocene at many localities in central Honshu and Shikoku, Japan (Miki, 1961).

2.2.28 Trochodendraceae

This family includes the extant east Asian vesselless genera Trochodendron and Tetracentron.

Trochodendron has one species, T. aralioides, distributed in Japan, Korea, and China (Taiwan) at elevations of 300 to 2700 m. It is an evergreen tree found in broadleaved forest or mixed broadleaved and evergreen forest. In the paleobotanical record, Trochodendron is known based on fruiting racemes from the Eocene of Washington (Fig. 58; Pigg et al., 2001) and British Columbia (Pigg et al., 2007), the Miocene of Idaho and Oregon (Fig. 56: Manchester et al., 1991; Fields, 1996: 304–307), the Miocene of Kamchatka (Fig. 57; Chelebaeva & Chigayeva, 1988) and Japan (Manchester et al., 1991). In Japan, the genus is also known from the mid-Pleistocene of central Honshu (leaf and fruits, Onoe, 1989) and Upper Pleistocene of Bosa Peninsula (fruits with seeds, Kokawa, 1966). Leaves found in association with the Trochodendron infructescences from the Middle Eocene of Republic, Washington (Pigg et al., 2001) resemble those of extant Trochodendron in thick texture (probably evergreen) and small appressed teeth typically confined to the apical half of the lamina, but they differ from leaves of the single extant species of the genus by having palmate venation, which is presumed to be a primitive character, shared also with Tetracentron. The leaves from the Middle Eocene of McAbee, British Columbia are more similar in venation to those of the extant species, but frequently differ by the presence of a pair of basilaminar extensions (Pigg et al., 2007)

Figure 56–59.

Trochodendraceae: Extant and fossil infructescences of Trochodendron. 56.Trochodendron sp. Middle Miocene of Emerald Creek, Idaho, UF 9575. 57.T. kamtschaticum Cheleb. & Chig. from early Middle Miocene of Kavavlya, Central Kamchatka, GINRAS 725–121. 58.T. nastae Pigg, Wehr, Ickert-Bond from early Middle Eocene of Republic, Washington, USA, USNM 537360. 59. Extant T. aralioides. Scale bars=1 cm.

Tetracentron has one extant species, T. sinense, which is a deciduous tree that lives in southern China, Bhutan, northeastern India, northern Burma, eastern Nepal, and northern Vietnam. Tetracentron has been recognized on the basis of its characteristic leaves from the Eocene of Princeton, British Columbia and Republic, Washington (Pigg et al., 2007) and from the Middle Miocene to Late Pliocene of Japan (Ozaki, 1987). The distinctive vesselless xylem of Tetracentron was also identified from the Miocene of Japan and carefully distinguished from that of Trochodendron (Suzuki et al., 1991). This genus has also been confirmed from the Miocene of Idaho, USA, based on well preserved in-fructescences (Manchester & Chen, 2006). The fruit morphology of the fossil matches that of the extant species, and the characteristic persistent recurved styles of these fossils bear adhering pollen matching that of extant extant Tetracentron. Similar fruits, along with Tetracentron leaves and dispersed pollen, have more recently been recognized from the Miocene of Iceland (Grímsson et al., 2008), indicating that the genus may have passed into Europe as well, but no fossil records are yet known from Europe.

2.2.29 Ulmaceae

Hemiptelea has one extant species, H. davidii, distributed from northeastern to southern China and Korea at elevations up to 2000 m. The fruits have curved endocarps with an enveloping asymmetrical wing. Such fruits are confirmed from the Miocene of Poland (Lańcucka-Środoniowa, 1967) and Ukraine (Dorofeev, 1982). Fruits and wood from the Pleistocene of central Honshu (Minaki et al., 1988) indicate that the Asian range of this genus formerly extended to Japan.

2.3 Patterns Observed

Table 1 provides a listing of the extant endemic genera of seed plants from eastern Asia, highlighting those which are also known from the fossil record, and summarizing their modern geography range, and growth form. Despite the emphasis that has often been given to endemic taxa represented in the broader paleobotanical record, it is obvious from this compilation that only a small fraction of the genera endemic to eastern Asia have confirmed fossil occurrences. Excluding the genera whose recognition in the fossil record remains tentative (e.g., Appendix 1), we calculate that only about 9 percent of those now endemic to eastern Asia are represented in the fossil record (54 genera known as fossils, of 596 extant genera).

Among the eastern Asian endemic seed plant genera known from the fossil record, 13 are gymno-sperms, i.e., Ginkgo and conifers (Table 2), and 36 are angiosperms (including those in Table 3, plus Euptelea, Euryale, Koelreuteria, Pterostyrax, and Tripterygium). Most are woody, including trees, shrubs, and, in the case of Sargentodoxa and Sinomenium, lianas. Only 4% of those known in the fossil record (Euryale and Trapella) are herbaceous, whereas among all the extant endemic genera (including those for which no fossil record is confirmed), 358 (60%) are herbaceous. Given that herbaceous genera are, in general, poorly represented as fossils, regardless of whether one focuses on regional endemics or on particular systematic groups, it is also of interest to examine the statistics with attention to the woody representatives. Of the 238 extant woody genera endemic to eastern Asia (Table 1), 52 genera (21%) are known in the fossil record.

The eastern Asian endemic plants considered here are a subset of a larger group of Asian endemics that include plants extending farther southward. Thorne (1999) listed additional oriental taxa whose area of endemism extends southward to Malesia. These tend to be plants with preference for tropical conditions. Examples of such genera distributed now in southeast Asia, which also have good fossil records in the Tertiary of North America and/or Europe, include Actinidia, Anamirta, Castanopsis Cyclea, Diploclisia, Mastixia, Nypa, Rhodoleia, and Sabia (e.g., Mai, 1980, 2001b; Manchester, 1999). These and others, some with ranges extending even to New Guinea and/or Australia, are outside the scope of the present treatment.

2.3.1 Collective fossil histories

Tables 2 and 3 (pp. 11–13) summarize the geographic and stratigraphic records of gymnosperm and angiosperm genera endemic to eastern Asia with accepted fossil records. These tables are similar to those presented by Mai (1980, 1995) and Manchester (1999) but emended to include newly recognized occurrences, and taxonomic and stratigraphic revisions. The data and references used to draw the ranges of each genus are summarized in the preceding section of this article. Although this study is mainly concerned with comparisons at the generic level, we acknowledge that the genus rank is an artificial category of taxonomic convenience, and that taxonomic ranking traditions differ among different clades of angiosperms. Thus, it is not surprising that similar geographic patterns may be observed at different taxonomic levels. The mono- and oligotypic families Trochodendraceae, Cephalotaxaceae Cercidiphyllaceae, Eucommiaceae, and Ginkgoaceae, are eastern Asian in modern distribution, but were widespread in the Northern Hemisphere during the Tertiary. At the infrageneric level, subsection Calyptranthess of Hydrangea illustrates the same geographic pattern.

Another point for consideration is the inherent bias of this study toward “living fossils”, i.e., extant genera for which morphological stasis has applied, allowing them to be recognized far back into the Tertiary, and, in the case of some conifers, even to the Cretaceous. This means these taxa have survived for millions of years, essentially unchanged in a suite of diagnostic morphological characters, in order for the fossils to be directly recognizable through comparisons with extant taxa. Extinct genera, including taxa that may have belonged to more rapidly evolving clades, are, by default, excluded from this treatment. Extinct genera commonly co-occur in fossil assemblages alongside the extant genera considered here (e.g., Reid & Chandler, 1933; Manchester, 1994). Northern Hemisphere examples of extinct genera showing various patterns of disjunction and endemism at different intervals of the Tertiary were summarized previously (Manchester, 1999).

It is clear from Tables 2 and 3 that most of these genera have a refugial modern distribution that arose when formerly widespread genera became extinct over large parts of their original distribution, but were able to survive in parts of eastern Asia. This is parallel to the history of some of the modern genera endemic to North America such as Sequoia, Decodon, and Comptonia (Ferguson et al., 1997; Thorne, 1999). The effects of cooling climate and glaciation through the Pliocene-Pleistocene interval explains many of the geographic range reductions of the particularly in Europe and North America, that resulted in the survival of these taxa in relictual areas.

2.3.2 Subregional distribution of paleoendemic genera

The eastern Asian endemic genera represented in the fossil record may be classified into geographic subgroups according to their modern characteristic distribution (Wu, 1998), of which three patterns are most prominent: Sino-Japanese, Sino-Himalayan, and broadly distributed eastern Asian.

The Sinojapanese region, in which the following genera occur, Cercidiphyllum, Cryptomeria, Disanthus, Euscaphis, Hemiptelea, Hovenia, Paulownia, Phellodendron, Platycarya, Schizophragma, Tripterygium, and Weigela, includes many more genera with known fossil representatives than does the Sino-Himalayan region. Among the numerous Himalayan and Sino-Himalayan genera (149 listed by Wu, 1998), only Tetracentron and Toricellia are known as fossils. Among the genera that are endemic exclusively to the Korea-Japan region (42 genera listed by Wu, 1998), Sciadopitys is the only one confirmed in the fossil record. Among the extant genera “characteristic of the Central China Province” (Wu, 1998) several have good fossil records: Cathaya, Davidia, Dipteronia, Eucommia, Metasequoia, Sargentodoxa, and Tapiscia. Genera with a broader “eastern Asian pattern of distribution” (87 listed by Wu, 1998) that are recognized in the fossil record include Actinidia, Cephalotaxus, Choerospondias, and Koelreuteria. In terms of numbers of surviving genera, the central part of China, such as Hubei and eastern Sichuan, may be regarded as a hot spot for the survival of these paleoen-demics. Did they also originate there?

2.3.3 Exotic vs eastern Asian origins

Although most of the conifers now endemic to eastern Asia have long records in Asia as well as Europe and North America (Table 2), most of the angiosperm examples have only later occurrences in Asia. In many instances the earliest available fossil records of the “east Asian endemics” are in other northern continents but not Asia (Tables 2, 3). This may be due in part to less intensive-sampling of the Asian fossil record, and it does not refute the possibility of Asian origins for these genera. However, if the discrepancy is taken at face value, it implies that many of these genera arrived relatively recently in Asia after an earlier history in Europe and/or North America, which would imply that they evolved outside of Asia. Euptelea and Thujopsis are the only examples we encountered of genera now endemic to eastern Asia whose fossil records are apparently confined to eastern Asia. Qian (2001) listed Actinodaphne, Machilus, Platycladus as additional examples of this pattern, but we have been unable to confirm the validity of those paleobotanical identifications.

Citing similar observations on Chinese endemic genera and their widespread fossil occurrences, Ferguson et al. (1997, p. 360) concluded “Many botanists have been misled by the presence of numerous relict genera in southern and western China into thinking that this area represents the centre of origin of these taxa.” The paleobotanically represented genera summarized here mostly have fossil ranges outside of Asia, indicating that the present distribution is more a matter of place of survival than place of origin.

On the other hand, we cannot ignore the high proportion of extant genera endemic to eastern Asia with no known fossil record (92%, Table 1). These include most of the herbaceous representatives, and it is likely that many of them originated in eastern Asia as previously proposed (e.g., Takhtajan, 1969; Wang, 1988), in association with uplift of the Himalayas. This tectonism created new environments that may have been responsible for a high level of East Asian neoendemism (Lu, 1999).

2.3.4 Routes of Intercontinental Dispersal

The dynamic patterns of geographic dispersal of plants through the Tertiary are well illustrated by plants with modern disjunct distributions in the Northern Hemisphere (Latham & Ricklefs, 1993; Milne & Abbott, 2002; Donoghue & Smith, 2004). Such cases of disjunction, as well as endemism, reflect changing configurations of land and sea, and climate. Barriers to dispersal may have been oceans and straits, and in some cases, desert areas (Tiffney, 1985; Tiffney & Manchester, 2001). Range expansion between Asia and other northern continents was controlled in part by: 1) the Turgai seaway which isolated Europe from Asia from the Late Cretaceous to early Tertiary, and 2) the Bering land bridge. The relatively high latitude of the Bering connection apparently excluded or at least “filtered” the transfer of thermophilic plants between North America and Asia, but apparently did not impede the spread of Pinaceae and Cupressaceae. The early Tertiary North Atlantic Land Bridge, providing a route of connection between North America and Europe, was at lower latitude than the Bering Land Bridge (Tiffney & Manchester, 2001). It is possible that some of the thermophilic genera shared between extant flora of China and the early Tertiary of western North America may have traveled “the long way around”: via the North Atlantic Land Bridge, with subsequent spread across Europe and the Turgai region to reach Asia. For example, Tapiscia, and Sargentodoxa, well documented from the Eocene of western North America, likely reached Asia via Europe, where they are also known as fossils, rather than by direct connection between Asia and North America.

The tectonic and climate influences on Tertiary plant distribution in the Northern Hemisphere were summarized by Tiffney and Manchester (2001). The main points are: Beringial crossings were possible (land connection, or only narrow separation) through much of the Tertiary, but the high paleolatitude may have been limiting to broadleaved evergreen trees due to cooler climate and/or winter darkness. Connection between North America and Europe is postulated to have occurred via the North Atlantic Land Bridge, connecting North America, Greenland, Iceland and Europe prior to the rifting apart of these land areas in the Late Eocene. The North Atlantic connection was at lower latitude than Beringia, and may have permitted the passage of more thermophilic plants. Connection between Europe and Asia became possible as the Turgai seaway retreated. Summarizing geological and paleontological evidence, Kubitzki and Krutzsch (1996) noted that during the climatic optimum of the Eocene “a belt of warm temperate climate in southern Laurasia, which bordered the Sea of Tethys, permitted the development of an exuberant laurophyllous flora. At this time many taxa now distributed in eastern Asia were present in North America and Europe. Eastern Asia was apparently excluded from participation in this floristic belt due to its pronounced aridity.”

Based on the geographic and stratigraphic distribution of genera, it is possible to infer some of the routes of dispersal important in the history of Asian paleoendemic genera. The Beringial connection linking eastern Asia and western North America appears to have been responsible for the passage of Davidia, Dipteronia, and Trochodendron, because there is no record of these genera as fossils in Europe, despite their high preservation potential (based on frequency of recovery in North American and Asian deposits). In other cases, colonization of Asia appears to have been from Europe as the Turgai seaway receded (e.g., Cyclocarya, Hemiptelea, Paulownia). The occurrence of Cercidiphyllum in eastern Asia during the Miocene could indicate immigration of the genus either from North America or from Europe, where species were already established in the Oligocene.

However, the record does not prove the directionality of movements. Finding a taxon at two different geographic locations A and B, indicates that there was a direct or indirect linkage between these places through time, but it does not specify whether the population at A, emigrated and colonized B, or vice versa. The recovery of older fossils from location A, than from B provides only weak evidence for directionality because the fossil record is so incomplete. Phylogenetic studies of extant genera with disjunctions across the northern continents may yield hypotheses of the directionality of prior intercontinental exchanges (Donoghue & Smith, 2004). Because the molecular phylogenetic approach requires extant species in multiple disjunct regions for comparative analyses, it cannot be directly applied in the case of endemic genera like those considered here; however the pathways illustrated by broader phylogenetic studies may include general patterns that were important in the history of endemic as well as disjunct genera.

2.3.5 Comparisons between Eastern Asia and North America

Qian (2001) compared patterns of endemism between eastern Asia and North America (north of Mexico) utilizing his database of extant genera of vascular plants. The study did not specifically compare eastern North America with eastern Asia, so it may be biased by including ocean-exposed western North America in comparisons with the landlocked western margin of eastern Asia. When these two areas were rigorously compared in terms of numbers of endemic genera, Qian found a significantly higher diversity of endemic angio-sperm genera in North America (981) than in eastern Asia (710), but a markedly higher diversity of coniferous endemic genera in eastern Asia (16) than in North America (4). Qian's analysis was taken to indicate that “in contrast to East Asia, which tends to have more paleoendemic genera, North America tends to have more neoendemic genera”. This hypothesis requires scrutiny from different approaches. From current data, we infer that only a small fraction of eastern Asian endemic genera are paleoendemic. There also appears to be a large number of neoendemic genera, not represented in the fossil record, that may have evolved along with the shifting environments associated with the Himalayan orogeny.

Appendix 1

Here we comment on additional Asian endemic genera that have been reported or suggested to be represented in the fossil record. In these instances, we explain why the fossil identifications are not accepted in this review.

Heptacodium (Caprifoliaceae) was identified based on leaves and fruiting calyces by Ozaki (1980). However, we have reexamined the fruits, and found that they have two whorls of persistent perianth, including an unlobed calyx which forms a rim around the apical edge of the fruit, and an inner whorl of persistent corolla with 5 prominent lobes, unlike the fruits of Heptacodium and other Caprifoliaceae, which have an impersistent cam-panulate corolla and 5-lobed persistent calyx. Another difference is that the fossil fruits are borne on long slender pedicels, rather than sessile. The affinities of these fruits do not appear to be with Caprifoliaceae. The leaves are similar to those of Heptacodium but without the corroborating fruit remains; we consider the identification to be questionable.

Hosiea (Icacinaceae) endocarps were identified by Mai (1987) from the Upper Paleocene of Gonna, Germany. However, the endocarps display overlapping characters of the extant genera Iodes, Hosiea and Natsiatum, and were subsequently placed in a fossil genus, Palaeohosiea by Kvaček and Bůžek (1995).

Fossil seeds attributed to Poliothyrsis (Flacour-tiaceae) by Mai (1980), lack the diagnostic wing, and are therefore difficult to diagnose as this genus rather than other related Salicaceae/Flacourtiaceae. Although the fossils which have been attributed to this genus have been illustrated and described in excellent detail both with light and SEM microscopy (Mai, 1980; Friis, 1985; Ferguson et al., 1998; Arbuzova in Budantsev, 2005), nobody has documented the seeds of extant Poliothyrsis in comparable detail to justify the assignment.

Kalopanax (Araliaceae) was recognized based on leaves from the Miocene Shanwang flora of China (Hu & Chaney, 1940) based on leaves. These leaves have 5 palmate lobes with widely spaced serrations (in contrast to the closely spaced, sharp teeth of extant Kalopanax species). Hu and Chaney (1940) did not provide characters to distinguish the leaves from those of Liquidambar, and it remains unclear if the generic assignment of the fossil leaves is correct. More recently, well preserved umbellate infructescences have been illustrated under the same name, Kalopanax acerifolium, also from Shanwang flora (Sun et al., 1999; pl. 45, fig. 1, pl. 37, fig. 1). The fruits are circular to ovoid in lateral compression, with an apical perianth bulge and at least two divergent styles. These infructescences clearly conform to the Araliaceae, but the generic assignment is in our opinion less certain.

Although Fokienia (Cupressaceae) was identified from the Paleocene of North America (Brown, 1962; McIver, 1992), closer study of anatomically preserved foliage, and new specimens with attached cones, (Guo SX, Kvaček Z, and Manchester S, in preparation) indicates that these species represent not extant Fokienia, but the extinct Cupressaceous genus, Ditaxocladus Guo & Sun (Guo et al., 1984).


This work was supported in part by US National Science Foundation grants EAR 9220079, 0174295, and INT 0074295 to SRM; National Basic Research Program of China (973 Program No. 2007CB411600) and Chinese Academy of Sciences (KSCX2-YW-R-136) to CZD; and in part by Research Project of the National Museum of Nature of Science (20077005) and the Monbusho Grant-in-Aid for Scientific Research (17540446) for KU. This work was also supported through SRM's participation in the NSF (NESCent)-sponsored Phytogeography of the Northern Hemisphere Working Group. Helpful advice and corrections were provided by Richard Dillhoff, Lutz Kunzmann, Zlatko Kvaček, Terry Lott, and Bruce Tiffney.