Systematics Section / ASPT
Hansen, Debra R. , Spicer, Greg S. , Patterson, Robert .
Phylogenetic relationships between and within Phacelia (Boraginaceae) sections Whitlavia and Gymnobythus.
The genus Phacelia (Boraginaceae), composed of roughly 200 species, is most diverse in California. Of the 93 natives, 39 are endemic to the state. Phacelia is divided into three subgenera; Cosmanthus, Howellanthus, and Phacelia. Subgenus Phacelia, the largest of these, is further divided into five sections. Gymnobythus and Whitlavia are two of the five sections in this subgenus. They grow in arid coastal areas from San Luis Obispo county south into Baja California, and into the western margins of the Mojave and Colorado deserts. These two sections share showy, campanulate flowers, lack of corolla scales, and round-to-ovate, simple leaves. They are differentiated by position of style cleft and presence (or absence) of stamenal appendages. Phylogenies based on nuclear ribosomal DNA and chloroplast DNA data imply that the two sections are not sister clades. Section Gymnobythus is monophyletic, and is sister to a clade which contains the polyploid P. magellanica complex. Section Whitlavia is non-monophyletic. Part of Whitlavia (P. nashiana and P. campanularia) is sister to the entire Euglypta/Miltitzia complex. Euglypta and Miltitzia are currently sections, and together they comprise most of the desert taxa plus one South American species (P. cumingii). The other part of Whitlavia (P. minor and P. parryi) is sister to a clade that includes subgenus Cosmanthus as well as the Euglypta/Miltitzia complex.
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1 - San Francisco State University, Department of Biology, 1600 Holloway Ave., San Francisco, California, 94132, USA
Presentation Type: Oral Paper
Location: Salon G - Austin Grand Ballroom/Hilton
Date: Wednesday, August 17th, 2005
Time: 2:15 PM