Croat, Thomas .
Phytogeography of the Araceae in the Guianas.
The Araceae of the Guianas number fewer species (23 genera and 165 taxa) than comparable areas of similar size in the western Andes but they are comparably rich in endemics with 50% of the species endemic to the Guianas and 70% endemic to eastern South America. The Guianas share with the Andes most of the same genera with only Chlorospatha absent among the widespread genera. In comparison to western South America, species diversity is much lower in the Guianas. Philodendron with 65 species (42 % endemic) is the largest genus. A subset of 14 species are in subgenus Pteromischum. Anthurium, with 22 species (68% endemic to eastern South America) is the second largest genus. The genus Caladium is unusually rich in the Guianas with 4 species, three of which are endemic to the region. Dieffenbachia has 9 species (55% endemic to the Guianas). Dracontium has 3 species, two of which occur only in Eastern South America. Heteropsis with 6 species is also primarily endemic to eastern South America. Monstera with 6 species in the Guianas has only one species endemic. Rhodospatha has 4 species with no endemics. Spathiphyllum has 6 species, four of which are endemic to Eastern South America and Stenospermation has 5 species, 4 of which are endemic to Eastern South America. Syngonium has 2 rather widespread species and Xanthosoma has 13 species, 8 of which are endemic to the Region of the Guianas.
The distribution of Araceae within the Guianas is uneven with fewer species in Guyana (78) and in Suriname (100) than in French Guiana (129). This may be due the presence of large areas of savanna vegetation in Suriname and Guyana where aroids are scarce as well by the fact that French Guiana is both more heavily forested and has a larger percentage of Amazonian species while still retaining a substantial percentage of species endemic to the Guianas.
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1 - Missouri Botanical Garden, Department Of Botany, P.O. Box 299, St. Louis, MO, 63166-0299, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Lindell C/Chase Park Plaza
Date: Tuesday, July 12th, 2011
Time: 1:30 PM