Systematics Section / ASPT
Cameron, Kenneth M. .
Leave it to the leaves: a preliminary phylogeny of Malaxideae (Epidendroideae, Orchidaceae) based on nuclear and plastid DNA sequence data..
Nuclear ribosomal ITS sequences and matK plastid DNA sequences were collected for more than 50 species of Malaxideae in order to develop a preliminary hypothesis of relationships among the genera and species in the tribe. Resulting cladograms are congruent, highly resolved, and well supported by bootstrap analyses. These phylogenetic reconstructions indicate that the traditional classification system of the tribe using characters primarily related to floral morphology does not reflect the evolutionary history of these taxa. Rather, the tribe is split into two major subclades: one of terrestrials species and another of epiphytes. Within the epiphytic subclade, taxa with equitant leaves (Oberonia) are monophyletic, whereas the remaining taxa (Liparis p.p.) have conduplicate leaves. Within the terrestrial subclade, there is a clear separation of taxa with plicate leaves (Liparis p.p. and Malaxis p.p.) opposed to taxa with conduplicate leaves (Liparis p.p. and Malaxis p.p.). Moreover, the terrestrial taxa with conduplicate leaves further segregate into a cluster of species with unifoliate vs. bifoliate leaves. There is also a strong geographic component to the relationships among these taxa. Although further sampling is needed before taxonomic changes should be made, this study is yet another that demonstrates the value of vegetative features over floral in classifying some groups of orchids.
1 - New York Botanical Garden, Cullman Program for Molecular Systematics Studies, 200th St. & Southern Blvd., Bronx, New York, 10458-5126, USA
Presentation Type: Paper
Location: Cottonwood A (Snowbird Center)
Date: Monday, August 2nd, 2004
Time: 10:00 AM