Embryological Studies in Phaseolus aconitifolius Jacq. Obs.

Abstract

The life history of Phaseolus aconitifolius Jacq Obs. is described in detail. The male archesporium is unicellular. The anther wall is made up of five layers of cells. The secretory type of tapetum consists of uninucleate cells Some of the sporogenous cells remain sterile and divide the anther locule into many chambers. The pollen grains are two celled at anthesis. The mature ovule is campylotropous, bitegmic, and crassinucellate The nucellus persists for long time at the chalazal end of the embryo sac. The female archesporium is unicellular The parietal tissue consists of three to four layers of cells The megaspore tetrad is linear. The monosporic embryo sac conforms to the Polygonum type. Fertilization is porogamous. Syngamy and triple fusion occur almost simultaneously Endosperm ab initio is free nuclear. However, part of it later becomes cellular. The free nuclear portion functions as an haustorium The mature seed is nonendospermic. The embryo follows the Onagrad type of development. The mature seed c...