Leaf Anatomy in Relation to Photosynthetic Characters of C₃ and C₄ Plants of Amaranthaceae

Out of 12 species of Amaranthaceae examined for leaf anatomy, 7 species exhibited Kranz type, while normal type leaf anatomy was observed in the other five species. A typical dorsiventral leaf anatomy with no evidence for radial arrangement of mesophyll cells around the prominent Kranz sheath was observed in Alternanthera pungens, Gomphrena decumbens and Gomphrena giobosa, whereas grass type radially arranged mesophyll was noticed in all the species of Amaranthus. The presence of colourless cells adjacent to lower epidermis was noticed in some species with Kranz anatomy while two or more layers of palisade was a constant feature in the non-kranz species. Leaf thickness and cell size were relatively smaller in the former group. Plants with Kranz type leaf anatomy showed higher photosynthetic rates, while higher photores-piratory ratio and higher transpiration rates were observed in the plants with normal leaf anatomy. Chl a/Chl b ratio and stomatal frequency ratio of upper to lower were higher in Kranz species.