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Abstract

The anthers are tetrasporangiate and the anther wall comprises five layers - epidermis, enfothecium, two middle layers and tapetum. Anther wall formation is of the basic type. At late stage the glandular (secretory) tapetum cells become binucleate and ultimately degenerated. As microsporogenesis progresses, middle layers become crushed and absorbed so that in the mature anther only the epidermis and endothecium remain intact. Tetrahedral tetrads are formed by simultaneous cytokinesis, followed by dissolution of callose and release of microspores. After microspore mitosis, pollen is shed at the two-celled stage. Mature endothecial cells are periclinally elongate, and moderate wall thickenings are present. C. brasiliense show two of the three evolutionary trends of the tapetum in Spermatophyta: 1) An intrusion of tapetum cells into the loculus, and 2) A better nutrition through direct contact with the spores in narrow anthers.