Phytologia {FchTna.T\ 1990) 68(2): 125-133. SYNOPSIS OF OLDENLANDIA (RUBIACEAE) IN THE UNITED STATES Edward E. Terrell Department of Botany, University of Maryland, College Park, Maryland 20742 U.S.A. ABSTRACT A synoptic taxonomic treatment for 0/rfen/anrfia (Rubiaceae) is pro-vided for five species occurring in the United States, including data on generic differences, keys to species, synonyms, brief descriptions, and habitats and distributions. Two of the species, O. boscii and O. uni-fiora, are native, and three species, O. corymbosa, O. salzmannii and O. callitrichoides, are adventive. KEY WORDS: Oldenlandia, Rubiaceae, systematics, United States. This synopsis provides a generic description of Oldenlandia, data on generic differences, keys to species, synonyms, brief descriptions, and habitats and distributions. These data are intended to provide a body of useful taxonomic information for this genus pending completion of a more detailed taxonomic treatment. Five species of Oldenlandia are included, of which two are native to the United States and three are adventive. Oldenlandia (tribe Hedyotideae; Rubiaceae) is a worldwide genus of warm, subtropical and tropical regions. Verdcourt (1976: 269) estimated the genus to have nearer 100 species, instead of the 300 sometimes estimated [e.g., Willis 1973). Most of the species are native to Africa, with smaller numbers in Asia, Australia and the Americas. Bremekamp (1952) in his extensive monograph of African species of Oldenlandia treated 61 species arranged in 16 subgenera and also dealt with 19 other genera more or less closely related to Oldenlandia. Authors of recent African floras recognized 12 Oldenlandia species in West Tropical Africa (Ilepper &^: Keay 1963), 7 species in Gabon (Halle 1966) and 37 species in Tropical East Africa (Verdcourt 1976). These authors did not recognize the occurrence of Hedyotis species in their regions, and Halle (1966) commented that Hedyotis is an Asian genus. Since 1753, the closely related Linnaean genera Hedyotis, Houstoma and Oldenlandia^ have been subjected to the shifting opinions of many system-atic botanists; some of this literature was reviewed by Fosberg (1943) and Bremekamp (1952). Verdcourt (1976: 269), while treating Oldenlandia, cited recent literature on these genera, including papers by Fosberg (e.^. 1943) and 125
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