XVI International Botanical Congess

Vernal pools have unique flora including Orcuttieae, a small tribe of C4 grasses comprising 3 genera and 9 species. Keeley (1998) was the first to suggest evolutionary relationships of Orcuttia, Tuctoria, and Neostapfia based on juvenile aquatic and adult terrestrial leaf morphologist, development of Franz anatomy and the operation of the C4 pathway of the tree genera of Orcuttieae. He discovered that Orcuttia aquatic leaves have C4photosynthesis but lack Kranz anatomy while Tuctoria and Neostapfia have C4 photosynthesis and Franz anatomy in submerged leaves. The purpose of this project was to use molecular data (nrDNA-ITS) to construct a phylogeny for tribe Orcuttieae. Preliminary results show Neostapfia appears to be basal in relation to Tuctoria and Orcuttia. This supports the hypothesis proposed by Keeley (1998) that the loss of Franz anatomy is a derived condition.