1. Paper chromatographic methods have been used to investigate the taxonomy of tea plants usually identified with Camellia sinensis (L.). Related species within the Thea section, and species from other sections of the genus were examined.
2. The following classes of phenolic substances were detected in tea: flavan-3-ols, depsides, flavonols, leuco-anthocyanins, and an uncharacterized substance IC.
3. Species within the Thea section of the genus Camellia are closely similar in chemical composition, the general pattern of which bears no obvious relationship to the chemical composition of non-Thea Camellias. Attention is drawn to depsides, which might have some bearing on species affinities.
4. Triglycosides of quercetin and kaempferol are found only in Camellia sinensis proper: this is the classical tea plant, commonly known as the China variety, and distinguished from all others by a small leaf with a dull surface.
5. It is possible to recognize two other forms of plant from which black tea can be made: each merits recognition as a taxon; but descriptions existing at the time of writing fail to make a valid nomenclatural distinction. Both forms have a relatively large, glossy leaf, but an unknown phenolic substance designated IC is found in one and not in the other.
6. The cultivated crop consists of crosses between the three forms of plant that we have described and possibly includes wide crosses with other taxa already recognized at species level.
7. The origin of crop populations is often associated (in the Tea Industry) with only two taxa, designated Assam and China variety. This is wrong. Not less than three taxa are involved; but the structure of the crop is such that populations cannot be satisfactorily defined by a nomenclatural system.
8. Chemical comparison of species showed an almost complete identity of C. reticulata with C. pitardii, and of C. taliensis with C. sinensis.
For the manufacture of black tea in north-east India, shoots are plucked from the bush at approximately weekly intervals. A shoot usually consists of two or three leaves and the growing apex (Wight and Barua, 1955). These, and comparable shoots from other species of Camellia, have been used in preference to mature organs, to relate chemical composition to taxonomic groups: in this way our observations are based upon standard
The foregoing group comparisons are inconclusive because of the small number of species examined; and greater significance attaches to comparisons at species level, some of which are of considerable interest: thus we are unable to detect any appreciable difference between C. reticulata and C. pitardii which are morphologically very similar.
In respect of the three species in section Thea, Figs, 1, 2 and 3 throw some doubt upon the validity of the distinction between C. taliensis and C. sinensis and support the specific rank of C. irrawadiensis recently recognized by Barua (1956).
Comparison of C. saluenensis and C. sasanqua shows that the former is the richer in flavonols, only the latter contains chlorogenic acid (and neochlorogenic acid), and only the former contains (-)-epicatechin. Apart from these differences there is a general chemical similarity between the two species, which does not, in itself, suggest separation in different sections of the genus.
Depsides are characteristic of tea and are absent from many of the non-Thea Camellias. Data in Table 2 suggest that depsides might be indicative of some important affinities, and it is therefore of interest to note the presence of these substances in C. reticulata, C. sasanqua and C. kissi.