Comparative anther and pistil anatomy of three flowering morphs of Acer oblongum Wall. ex DC. (Sapindaceae s.l.) and its adaptive significance
17 October 2017
Yadav, Neha; Pandey, Arun; Bhatnagar, AshokA comparative anatomical study of reproductive parts of the three floral morphs of Acer oblongum (Sapindaceae) was done to ascertain the functionality of the parts present and its adaptive significance. Individual trees of A. oblongum possess three types of flower morphs. Though morphologically all flowering morphs appeared to be bisexual, temporally the male or female function is suppressed to achieve successful cross-pollination. In addition, the role of endothecial thickenings in selective dehiscence of anther was also studied. Anatomical analysis showed the presence of fibrous thickenings in the cells of endothecium of staminate type I flowers. However, minimal opening of anther along the line of dehiscence was observed in hermaphrodite flowers that showed poor differentiation of endothecium. Although endothecium is formed in anthers of hermaphrodite flowers, the failure of anthers to dehisce is because not all the endothecial cells showed the presence of fibrous thickenings, especially towards the stomium. Mature pollen grains in hermaphrodite flowers were formed only after stigma divergence when the receptivity was already lost (after Stage 3). Pistil anatomy revealed functional embryo sac in only hermaphrodite flowers. Functionally male flowers, with undeveloped pistil, serve as the only source of pollen for fertilization.