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Keywords:

  • Borszczowia;
  • Chenopodiaceae;
  • Suaeda;
  • C4 plants;
  • C4 photosynthesis;
  • Kranz anatomy;
  • leaf types

Abstract: From the hygrohalophyte Borszczowia aralocaspica Bunge (Chenopodiaceae), a new leaf type with 1-layered chlorenchyma is described as “borszczovoid” and compared with other leaf types in subfamily Salsoloideae. The chlorenchyma is suspected to represent a unique C4 type. Evidence is cited from anatomical studies and documented by micrographs and Carbon isotope determinations (ä13C values). The 1-layered photosynthetic tissue combines all essential anatomical characters of a 2-layered chlorenchyma of regular C4 plants and is in intimate contact with concentrically arranged peripheral bundles. The ä13C values are − 13.03 ‰ from young stems and − 13.78 ‰ from leaves. The results are discussed in the anatomical, physiological and taxonomic framework. In addition, from distantly-related Suaeda species of section Conosperma the conospermoid leaf type is re-described. It is characterized by typical palisade and Kranz layers and differs from the C4 suaedoid type by an external water-storaging hypodermis and an arrangement of Kranz cells reminiscent of the atriplicoid type from subfamily Chenopodioideae. From eight other species of Chenopodiaceae ä13C values are given for the first time.