Embryological studies in compositae - III. A contribution to the embryology ofBlainvillea rhomboidea, Cass. (B. latifolia, DC)
InBlainvillea rhomboidea, Cass. the floral parts arise in acropetalous succession. The archesporium consists of two linear rows. of cells In the fully formed anther there is an epidermis, an endothecium, a middle layer, a tapetum and two linear rows of microspore mother cells. Tapetal cells become binucleate and are of the plasmodial type. Microspore tetrads are isobilateral, tetrahedral and decussate. Exine of the pollen grain is echinate. Shedding is at the three-celled stage as in the majority of Compositae. Endothecium shows faint fibrillar thickenings at the time of anther dehiscence.
Ovules are anatropus, unitegmic and tenuinucellate. A hypodermal archesporial cell directly functions as the megaspore mother cell. Embryo sac development is of the Polygonum type. More than one megaspore in the tetrad show signs of development. Organised embryo sac is six-celled with only two antipodals. A secondary multiplication of nuclei in the antipodal cells results in a variable number of nuclei.
Endosperm is of theab initio cellular type.
Embryogeny conforms to Asterad type.
Fruit wall has a thick layer of tannin cells in the hypodermal layers.