Galium grande (Baccogalium)

Galium hypotrichium var. tomentellum (Lophogalium)

My current research focuses on the evolution of plant breeding systems and systematics of Galium and related genera in the Rubiaceae (coffee family).

Various evolutionary pathways have been proposed to explain the evolution of dioecy, separation of reproductive organs on different individuals, from hermaphroditism. Polygamy, the occurrence of both hermaphroditic and unisexual flowers within a taxon, has often been considered an intermediate sexual form. Polygamy does not occur commonly among angiosperms and examining a group that contains both hermaphroditic and dioecious species, as well as polygamous species, will aid our understanding of the evolution of this particular sexual system.

The genus Galium is distributed worldwide and has traditionally been divided into 13 sections. Preliminary molecular analyses of the cpDNA trnT/F region confirm previous analyses by Manen et al. (1994) and Natali et al. (1995), demonstrating that Galium, as traditionally circumscribed, is polyphyletic.

This work has identified a clade comprised of members of three traditionally circumscribed sections - Baccogalium, Lophogalium, Platygalium - and the genus Relbunium.  The occurrence of polygamy, dioecy, and hermaphroditism within this group provides an opportunity to examine breeding system evolution.  A molecular phylogeny is being constructed for this clade to test two hypotheses: 1) that species exhibiting polygamy are evolving towards dioecy from a state of hermaphroditism, and 2) that polyploidy is correlated with the evolution of dioecy.

BIOL117/317 Plant Identification & Classification

University of Washington, Department of Biology

Olmstead Lab

University of Washington Herbarium (WTU)

Rancho Santa Ana Botanic Garden (RSA)

RSA Herbarium Database

Third International Rubiaceae Conference