An embryological study ofMimosa pudica Linn.

Abstract

1. The pollen grains are shed united together in quartets. Each pollen grain contains a generative and a tube nucleus. The tapetum remains uni-nucleate throughout. During the first metaphase, 24 bivalents have been counted. 2. The archesporium consists of three to four cells though only a single cell develops further. A parietal tissue of 4–5 cells in thickness is formed. 3. Megasporogenesis proceeds normally and the embryosac conforms to the monosporic eight-nucleate type. Synergids show the characteristic filiform apparatus and the polars may fuse before or during fertilization. Antipodals are formed as definite cells, and the degenerated remains may persist until fertilization. 4. Endosperm is free nuclear in the beginning and wall formation commences from the micropylar end stopping short of the lower one-third of the embryosac. The chalazal end contains free endosperm nuclei which aggregate simulating the basal apparatus with a tendency to grow into the chalazal region. 5. The first division of the fertilized egg is transverse while the second division which is vertical is belated in the upper cell. Later divisions are irregular and the embryo has no differentiated suspensor, being of the massive type.