A contribution to the embryology ofOlax wightiana wall

Summary

The floral parts arise in acropetal succession. Unicellular hairs are distributed over the floral parts. Plenty of tannin cells are found. The wall of the anther consists of five layers external to the tapetum. The tapetal cells are uninucleate at first, but later become binucleate, and are of the glandular type. The endothecium and the layer immediately below it are fibrillar. The microspores are arranged tetrahedrally, but occasionally show a decussate arrangement. The pollen grains have three and occasionally four pores and they are two-celled at the time of shedding.

The superior ovary is surrounded by a hypogynous disc. Three pendulous ovules arise from the mamelon, and project into the ovarian cavity around the central column.

The ovules are unitegmic, although this condition may not appear to be distinct during their subsequent growth, and they are tenuinucellate. At first they are hemianatropous, but later become anatropous.

A single archesporial cell functions directly as the megaspore mother cell. The development of the embryo sac conforms to the Allium type, and has been studied in detail. The embryo sac develops a cæcum within the ovule, which assumes a prominent haustorial function.