Pollinial morphology and pollen organization in some members of asclepiadaceae

Pollinial morphology of thirteen genera were studied with the help of LM and SEM. In addition to this, position of germ furrow was studied by in vitro pollinial germination. Nature of pollinial furrow is specific for each genus. It may be very close to the caudicle, opposite to corpusculum as in the case of Gymnema or may be away from caudicle as in Tylophora. In spherical forms the furrow may be at the corpuscular side or opposite to it. Germinating pollen grains without exine are coming out from the pollinia during germination. Generally size and shape of individual pollen grains are not specific but in genera like Asclepias, Caralluma, Daemia, Huernia and Hoya pollen grains located at the margin of furrow are longer. Pollen grains are non aperturate in all the genera coming under Cynanchoideae studied.