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The activities of C4 acid decarboxylation enzymes (NAD-malic enzyme, NADP-malic enzyme, and phosphoenolpyruvate carboxykinase), and the anatomy of photosynthetic organs (leaves, culms, bracts) were investigated in 30 species from 12 C3, C4, and mixed (C3+C4) genera of sedges. The sample incorporated representatives of the three previously known C4 anatomical types in the family (fimbristyloid, chlorocyperoid, and rhynchosporoid), and of six genera previously uninvestigated biochemically, including Eleocharis (six species). Eleocharis is variable for photosynthetic pathway: three species proved to be C3, two C4 (E. caespitosissima Baker and E. retroflexa (Poir.) Urban), and one (E. pusilla R. Br.) may be a C3-C4 intermediate. The C4 Eleocharis spp. exhibit a C4 anatomy ('eleocharoid') hitherto undescribed, and are NAD-ME type, in contrast to species of the other three C4 anatomical types examined …