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Pollen ultrastructure of Pentaphylacaceae and Sladeniaceae and their relationships to the family Theaceae

1999; Science Press; Volume: 21; Issue: 2 Linguagem: Inglês

0253-2700

Wei Xin, Fan X. K., Zhang Xiang Lan,

Lichen and fungal ecology

To elucidate taxonomic relationships among the families of Pentaphylacaceae, Sladeniaceae and Theaceae, pollen grains of 10 genera, ca.20 species representing three families stated above were examined by light, scanning electron, and transmission electron microscopes. The comparison of pollen morphology shows that the pollen grains of Sladeniaceae are very similar to those of Theaceae. Their pollen grains are oblate to nearly spheroidal and 3-colporate, from rugulate to rugulate-reticulate sculptures and exine structure consisting of thick tectum and columellae,and thin endexine. However, the pollen grains of Pentaphylacaceae are different relatively from those of Theaceae for having nearly psilate pollen surface and exine structure consisting of thin tecum, undeveloped columellae and thick endexine though the pollen shape(oblate)and aperture(3-colporate)are similar to those of Theaceae. As far as the pollen sculpture and exine structure are concerned, Pentaphylacaceae is more similar to Clematoclethra Maxim. of Actinidiaceae than to Theaceae. Palynologyical result supports to treat Sladeniaceae as a genus Sladenia under Theaceae, or as a subfamily of Theaceae.