Sem studies of seed coat in some asiatic vigna species and their taxonomic and phylogenetic significance

Seed morphology, hilum structure and cellular structure of seed coat of predominently cultivated and wild species of the genus Vigna in India were studied using scanning electron microscopy (SEM). The important species include mung bean Nigna radiata (L) Wilczek), urid bean (V. mungo (L.) Hepper), rice bean N, umbellata (Thunb.) Ohwi and Ohashi), moth bean N. aconitifolia (Jacq.) Marechal) and Pillipasera (V. trilobata Ail.) and their wild occurring closely related putative progenator forms particularly V. radiata (L.) var. sublobata Verde., V. mungo (L.) var. silvestris Lukoki, Marechal and Otoul, wild forms of V. umbellata and V. aconitifolia. Seed coat cellular structure and hilium were characteristic to each species and appeared to be species-specific. Considerable morphological similarties were observed between cultivated plants of V. radiata with its related wild species V. radiata var. sublobata, V. mungo with that of V. mungo var. silvestris and V. umbellata with its wild form. In V. aconitifolia, cultivated and wild types differed drastically in their seed coat surface pattern. SEM seed coat structure was found to be useful in establishing taxonomic and phylogenetic relationship in these Indian species of Vigna.