'7</.06 73 Vol. 85, No. 40, pp. 469-480 30 December 1972 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON STUDIES ON POLLEN MORPHOLOGY IN THE VELLOZIACEAE By Edward S. Ayensu Smithsonian Institution Washington, D. C. 20560 The family Velloziaceae contains about 250 species of peren-nial herbs and shrubs. Three or four genera are recognized from Madagascar, Southern Africa, Arabia, and South America. Vellozia, which is the type-genus, has the largest number of species (about 170); Barbacenia is the second largest genus with about 80 species. Xerophyta constitutes all the Madagas-can and African species except for one, Talbotia elegans Balfour, which occurs in South Africa (cf. Smith and Ayensu, in press). In recent years there has been heightened interest in the Velloziaceae because of their phytogeographical and evolution-ary implications ( Ayensu, in press ) . A treatment of the Amer-ican species by Smith ( 1962 ) brought the family up to date, and since that time I have been studying the vegetative anatomy of the family with the intent of amassing further data to improve the systematics of the group (cf. Ayensu, 1968; 1969a, b ) . One of the problems in this family is how to resolve the highly controversial generic limits of the taxon. The aim of this study, therefore, is to add new positive correlative information from pollen morphology to the existing characters that have been building up in recent years. Erdtman (1963) described the pollen of the Velloziaceae as being 1-sulcate of two distinct types, Barbacenia-Barbaceniopsis con-sisting of single grains while Vellozia grains are united in tetrads. Barbacenia grains are also smaller than those of Vellozia, in fact, in a ratio of about 1:2. His study was based on 16 species from both Africa and South America. A more 40— Proc. Biol. Soc. Wash., Vol. 85, 1972 (469)
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