Embryological studies of Oxalis debilis Kunth

The study of pollen and female gametophyte development of Oxalis debilis was carried out to elucidate the reasons for the absence of seed production in this species. The formation of an incomplete callosic wall separating the microspores of the tetrad was observed; therefore, cytoplasm connections were present between the microspores. Microspores of different sizes and with different grades of vacuolation were observed in the mature anther. Only few microspores divide mitotically and form the generative and vegetative cell. The cytoplasm of the vegetative cell may accumulate different substances in reserve. Pollen grains are 8–12?colpate, and the morphology and electron density of the exine varies. Because flowers in full anthesis have all ovules at the megasporocyte stage with the nucellar epidermis intact, fecundation could not occur. The production of only a few viable pollen grains and the absence of successful megagametophyte development prevent fertilization and account for the absence of fruits and seeds formation.