Revision of Dicorynia (Cassieae,Caesalpiniaceae)

A combined taxonomic revision and wood anatomical study ofDicorynia, a South American genus of legumes that is unusual in both its floral and wood anatomy, is presented. Two possible evolutionary pathways leading to the unique 8-to 10-thecate anthers are discussed, and it is concluded that apical proliferation of the thecal primordia is the more likely. Gross and microscopic features of this silica-accumulating wood are given in detail and contrasted with other legume woods especially those containing silica. Economic uses of the trees, especially the wood ofD. guianensis, are discussed particularly in regard to marine construction. It is suggested that the high resistance of this wood to marine borers lies not so much in its silica content as to the presence of some other chemical. Based on the similarity of floral and fruit structures, the number of species is reduced from 7 to 2:D. guianensis in the Guianas andD. paraensis in the Amazonian region. Vegetative variations in the Amazonian population, previously given species rank, are reduced to 5 new varieties ofD. paraensis.