Lane, Christopher , Patterson, Robert , Gilbert, Cynthia .
Biogeography of Phacelia dalesiana and P. greenei (Boraginaceae).
Phacelia (Boraginaceae) has diversified the most within the state of California where 93 of its taxa are found, 39 of which are endemics. While studies have been done in order to determine relationships among certain subgroups, no comprehensive phylogenetic analysis of Phacelia currently exists. Phacelia dalesiana, a small perennial herb, is a very narrow endemic restricted to serpentine soils near Scott Mountain in the Siskiyou ranges of Northern California. Where the majority of Phacelia is characterized by their coiling and tightly bunched inflorescence, P. dalesiana has a vastly different morphology, being short in stature and having an open corolla. Based on distinct appearance, Constance recognized it as a separate monotypic subgenus, Howellanthus. It has been implied that subgenus Howellanthus is sister to the rest of Phacelia, but lack of current sampling of it and other subgenera renders a clear phylogenetic interpretation of Phacelia incomplete. The annualPhacelia greenei is a second narrow endemic from the Scott Mountain area. and occurs within a kilometer of populations of P. dalesiana. Despite their similar ranges and their apparent soil endemism, these two species appear morphologically very distinct within the genus. Placement of P. dalesiana and P. greenei within the genus awaits a complete phylogenetic study of Phacelia, upon which further study can resolve questions pertaining to the subgeneric status of Howellanthus, its closest relatives, and its position as sister to the rest of Phacelia. Do the similar ranges and patterns of endemism in each species represent a single or two independent events? As both species are listed in the California Native Plant Society's Inventory of Rare and Endangered Plants of California, management of this rare species will be strongly influenced by the results of this study.
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1 - San Francisco State University, Department of Biology, 1600 Holloway Ave., San Francisco, California, 94132, USA
Presentation Type: Array
Location: Salon C, D & E - Gov Ballroom/Hilton
Date: Tuesday, August 16th, 2005
Time: 12:30 PM