Studies on the development of gametophytes and endosperm in Jamesbrittenia microphylla (Scrophulariaceae) with reference to its systematic position

Abstract

In Jamesbrittenia microphylla (L.f.) Hilliard, the anther is bilobed, bilocular and bisporangiate. The microsporangium wall comprises epidermis, endothecium, middle layer and tapetum. Cytokinesis of pollen mother cells is simultaneous Microspore tetrads are tetrahedral. The triaperturate pollen grains are shed at the 2-celled stage. Ovules are anatropous, tenuinucellate and unitegmic. The development of the embryo sac is of the Polygonum type. An endothelium surrounds the mature embryo sac. Endosperm development Is ab initio cellular. Both chalazal and micropylar haustoria are well developed. The chalazal haustorium is 2-celled and the micropylar haustorium Is 4-celled. These results are compared with earlier work In the Manuleae tribe and the close relationship between Manuleae and Selaglneae is emphasized.