Authors: Wang, Yin-Zheng; Li, Jun; Liang, Han-Xing; Wu, Zhen-Yi
Publication: Acta Botanica Yunnanica
Year: 2001
Genera: Whytockia

The embryology of Whytockia hekouensis Y.Z.Wang, as a representative of the genus Whytockia, was investigated in order to provide information on the systematics of the genus. The anther wall comprises four layers-epidermis, endothecium, middle layer and tapetum. 2-3-nucleate cells are frequently observed in the tapetum. The anatropous, unitegminal and tenuinucellar ovules, and the embryo sac of the Polygonum type conform to those of the most members of the Gesneriaceae. Twin megaspore mother cells occasionally occur during megasporogenesis. The development of the endosperm is of cellular type. The micropylar haustorium of Whytockia is 2-celled uninucleate in the early development and 2-celled binucleate of 4-celled uninucleate, and sometimes multi-celled in the late development, while the chalazal haustorium is binucleate. The extra – micropylar structure has been observed during the development of the micropylar haustorium. The development of the onagrad type embryo consumes up the endosperm except one layer that remains in the mature seed. The coat of a mature seed consists of two layers which develop respectively from the outer epidermal cells and the endothelial cells of the integument. The embryology of Whekouensis is compared and discussed with that of others in the Gesneriaceae.