Systematics/Phytogeography / Taxonomie/ Section
Sweeney, Patrick .
Phylogeny and floral development in Garcinia (Clusiaceae).
The pantropical genus Garcinia (Clusiaceae), a group comprised of more than 250 species of dioecious trees and shrubs, is a common component of lowland tropical forests and is best known by the highly prized fruit of mangosteen (G. mangostana L.). The genus exhibits as extreme a diversity of floral form as is found anywhere in angiosperms. Results of a recent phylogenetic study reveal that Garcinia species fall into one of two major clades, one characterized by the occurrence of nectariferous floral structures of uncertain derivation such as antesepalous appendages and intrastaminal disks and rings, and the other by their absence. These nectariferous floral structures have been hypothesized to represent an outer whorl of stamens, and this is supported by studies of species representing other Clusiaceae and closely related families that have structures similar to those in Garcinia. However, the position of these structures in mature Garcinia flowers does not support the hypothesis that they represent an outer whorl of stamens. To better understand the nature of the appendages, disks, and rings in Garcinia, floral development was studied in a sample of six Garcinia species. An outer whorl, staminodal origin for the disks and appendages is not supported by timing of development or position as disks and appendages are not apparent until late in development and the disks arise in the center of flower. These data also reject a gynoecial origin for these structures and suggest that they are intrastaminal receptacular nectaries.
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1 - Yale University Herbarium, Peabody Museum of Natural History, P.O. Box 208118, Yale University, New Haven, CT, 06520, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Wednesday, July 30th, 2008
Time: 3:30 PM