Faden, Robert , Layton, Daniel J. , Burns, Jean H. , Wurdack, Kenneth J. .
Diversity and Relationships in Commelina (Commelinaceae) .
With an estimated 170 species, the nearly cosmopolitan Commelina is the largest and most widespread genus of Commelinaceae. Its center of diversity is tropical Africa, with about 100 species, but smaller radiations have also occurred in Madagascar, North and South America, tropical Asia and Australia. With a conservative bauplan - leafy bracts (spathes) enclosing small numbers of monosymmetric flowers -- and usually mediocre herbarium specimens, due to poor flower preservation, the frequent absence of capsules and seeds, and inadequate collectors' notes, Commelina is very difficult to study without access to living plants and spirit collections. Long term research and recent floristic treatments have revealed: 1) large numbers of new species and infraspecific taxa, particularly in Africa; 2) cryptic species that have been long overlooked, even in well-collected areas; 3) variation in common, widespread species that is resistant to formal classification; and 4) a suite of new characters that is useful for distinguishing taxa and evaluating relationships among them. Characters that can be used to separate species include: spathe and floral morphology; flower color; capsule dehiscence; adaptations for animal dispersal of seeds; leaf anatomy; types of trichomes present and their distributions on vegetation and reproductive organs; and basic chromosome number and ploidy. The only infrageneric classification of Commelina is that of Clarke (1881), who recognized two subgenera, based on ovule number per locule, and three sections in each subgenus, based on capsule locule numbers and dehiscence. Preliminary phylogenetic studies, including Burns et al. (in press), do not support Clarke's classification, but they are not yet far enough advanced to propose an alternative system.
Log in to add this item to your schedule
1 - University of Missouri-St. Louis, Biology, 223 Research Bldg. One University Blvd. St. Louis, MO 63121, USA
2 - Case Western Reserve University, Biology, 2080 Adelbert Road, 307 DeGrace Hall, Cleveland, OH, 44106-7080, USA
3 - Smithsonian Institution, Botany, MRC-166 National Museum Of Natural History, PO Box 37012, WASHINGTON, DC, 20013-7012, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Lindell A/Chase Park Plaza
Date: Wednesday, July 13th, 2011
Time: 11:15 AM