SPOROGENESIS AND GAMETOGENESIS OF ENDANGERED ADENOPHORA LOBOPHYLLA HONG (CAMP ANULACEAE)
濒危植物裂叶沙参的大小孢子发生及雌雄配子体发育

Reported in this paper are the microsporogenesis, megasporogenesis and the development of male and female gametophytes of the endangered species Adenophora lobophyl-la. The anther is four-sporangiate with its wall composed of four layers: epidermis, fibrous endothelium, middle layer and glandular tapetum of binucleate cells. The cytokinesis of mi-crospore mother cell in meiosis is simultaneous, and tetrads are tetrahedral. Pollen grains are 2-celled at the dispersal stage. Ovule is anatropous, unitegmic and tenuinucellate with a hy-podermal archesporial cell developing directly as the megaspore mother cell which undergoes meiotic division and then forms a linear tetrad. The embryo sac is of Polygonum type. The polar nuclei fuse before fertilization. An endothelium differentiates when the uninucleate embryo sac forms. Comparative studies were made with the closely related and widely distributed species A. potaninii. No differences between them were found. No obstacle to sexual reproduction in this endangered species was observed. As a conclusion, no endangering factors were found to influence the sporogenesis and gametogenesis of A. lobophylla. According to our observision and the references on embryological studies of the Campanulaceae(s. 1. ), there is no evident differentiation in sporogenesis and gametogenesis in this family.