A remarkable new leaf type with unusual photosynthetic tissue in a central Asiatic genus of Chenopodiaceae

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 C-4 type. Evidence is cited from anatomical studies and documented by micrographs and Carbon isotope determinations (delta(13)C values). The 1-layered photosynthetic tissue combines all essential anatomical characters of a 2-layered chlorenchyma of regular C-4 plants and is in intimate contact with concentrically arranged peripheral bundles. The delta(13)C 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 C-4 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 delta(13)C values are given for the first time.