XVI International Botanical Congess

Tetraplasandra is a genus comprised of six endemic species, Munroidenron is a monotypic genus, and Reynoldsia (six species, with one Hawaiian endemic), are thought be closely related. Tetraplasandra species are also very closely related, probably evolving from a single ancestral introduction. However, the taxa exhibit a wide range of floral morphologies. The androecium occurs in one or two whorls and stamen number ranges from 5 - 66. The gynoecium varies in carpel number from 2 - 13, and ovary position from inferior, to partially inferior, to superior. The occurrence of hypogyny (in T. gymnocarpa) is unique among Araliaceae and is thought to have evolved in Hawaii from epigynous ancestors. We used ITS and 5S-NTS ribosomal DNA sequence data to construct a phylogeny. Phylogenies based on ITS sequence data showed that the three genera are monophyletic and have evolved from a single common ancestor. However, the relationships among Tetraplasandra species were not resolved using ITS data. 5S sequence data was used to resolve relationships among these species. There are four clades resolved in the 5S tree. Tetraplasandra hawaiiensis is the ancestral species and there is a large unresolved clade which contains epigynous species. Nested between these two clades are T. gymnocarpa and T. kavaiensis, which have superior to partially inferior ovaries and fewer stamens and carpels. This suggests that hypogyny evolved in Hawaii from an epigynous ancestor. This research is supported by the Lewis B. and Dorothy Cullman Foundation.