Megasporogenesis, Microporogenesis and Formation of Female and Male Gametophyte of Catalpa specioca

The megasporogenesis, microsporogenesis and formation of female and male gametophyte of Catalpa specioca were observed using conventional paraffin section technology. The results showed that each flower of C. specioca contains five stamens,two of which are fertile stamens and the others are staminodia. The anther of the fertile stamen is tetrasporangiate, and its anther wall is composed of four to six layers: epidermis, endothecium, one to three middle layers and tapetum. The development of anther wall is basic type and tapetum belongs to glandular type. Archesporium is milti-provenace. Simultaneous cytokinesis in microspore mother cells follows meiosis to produce tetrahedral tetrad as well as isobilateral tetrad. Every compound pollen grain comprises four microspores derived from one microspore mother cell. Pollen grains are 2-celled when shed. The ovule is anatropous, bitegminous and tenuinucellate. The archesporial cell below nucellus epidermis functions directly as the megaspore mother cell. The chalazal megaspore of linear tetrad develops into a Polygonum-type embryo sac. In the same bud, the stamen develops earlier than the pistil, but maturates almost at the same time.