Taxon 31(3): 535-539. August 1982 Systematic Status of the Genus Kleinodendron (euphorbiaceae)

The Euphorbiaceous genus Kleinodendron was described by Smith and Downs (1964) on the basis of specimens collected by Reitz and Klein in Santa Catarina province, Brazil. The authors noted that fruiting specimens had a resemblance in aspect to Actinostemon, but on the basis of the flowers proposed a new genus Kleinodendron, which they assigned to the tribe Clutieae sensu Pax and Hoffmann (1931). Since there was some doubt as to the affinities of the new genus, Dr. Smith persuaded Dr. William Stern to undertake an anatomical survey of the tribe Clutieae in order to better establish the systematic position of Kleinodendron. As a result of his study, Stern (1967) concluded that "there are no anatomically related objections to the inclusion of Kleinodendron riosulense in the Clutieae as delineated by Pax (1890) and amplified by Pax and Hoffmann (1931)." In his interesting survey of the wood anatomy of genera which had been assigned to the tribe Clutieae by Pax and Hoffmann, Stern noted that the wood structure is moderately specialized with considerable variation, and pointed out that Microdesmis and Pogonophora are strikingly divergent from the other genera in their characteristics. He concluded that both these genera should be excluded from the Clutieae, and accepted (with some reservation) the proposal by Forman (1966) to transfer Microdesmis to the segregate family Pandaceae. More recently, I have created a separate tribe Pogonophoreae for Pogonophora, which has distinctive floral characters in addition to the anatomical ones pointed out by Stern (Webster, 1975). Although he cited the palynological study of the Euphorbiaceae by Punt (1962), which indicated considerable heterogeneity in pollen characters within the tribe Clutieae, Stern made no specific comparisons between xylem characters in the genera with "Croton type" pollen and those with "non-crotonoid" pollen. This was unfortunate because, as indicated by Punt (1962) and Webster (1967, 1975), the "crotonoid" exine ornamentation pattern found in many "uniovulate" genera of Euphorbiaceae appears to be highly significant taxonomically. Of the subtribes of Clutieae as defined by Pax and Hoffman (1931), "crotonoid" pollen occurs in the Acidocrotoninae, Clutiinae, Codiaeinae (ex p.), Jatrophinae, and Ricinodendrinae (Punt, 1962; Webster, 1975; Webster and Lynch, ined.). Since the pollen of Klei-