Morphology, ultrastructure and pollen germination in Ibicella lutea (Martyniaceae)

Abstract

Pollen morphology, ultrastructure and germination mode of Ibicella lutea was investigated and documented using light microscopy (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Ibicella pollen is clypeate, spheroidal, apolar, inaperturate, insulated, large, with an average diameter of 80 μm. The pollen wall is formed in the insula by two distinct layers; the outer layer, the exine, which is semitectate, with ectexine constituted by columellae, tectum and foot layer and the granular endexine, being the only layer between the insulae and the inner layer, the thick intine. The generative nucleus is of irregular shape and the vegetative nucleus is spheroidal. This is the first report of the presence of microbodies within the vegetative cell in pollen of Martyniaceae. The probable function of the microbodies in the lipid metabolism of the vegetative cell is discussed. The pollen tube emerges through the thinner areas of the wall between the insulae. In these areas the cytoplasm shows vacuoles and secretory vesicles produced by dictyosomes.