Systematics Section / ASPT
Cohen, Jim .
Phylogeny and breeding system evolution in Lithospermum (Boraginaceae; Lithospermeae).
THE Boraginaceae include ca. 110 genera and 1,600 species, assigned to ca. 6 tribes, including the Lithospermeae, which include ca. 20-30 genera. Of these genera, only Lithospermum, which includes ca. 45 species and is the largest genus in the tribe, occurs in both the Old and New Worlds. Although Lithospermum is widely distributed, its center of diversity is in Mexico and the southwestern United States where two thirds of the species are found. The genus has not been thoroughly revised since the 1950s when Ivan Johnston treated it (I.M. Johnston, 1952, J. Arnold Arbor. 33:299-366). He also reviewed the tribe, but there has been no modern tribal-level phylogenetic analysis to test the monophyly of the genera. A previous phylogenetic analysis of Lithospermum resolved some species relationships, but left many relationships unresolved (B. Ralston, Ph.D. dissertation). The species of Lithospermum exhibit a range of variation in corolla color, texture, size, and other features related to breeding system. Corolla colors include white, orange, yellow-green, and shades of yellow, and various species exhibit herkogamy, heterostyly, and cleistogamy. A preliminary phylogenetic analysis of Lithospermum and related genera has been conducted, with attention to floral features as they relate to breeding systems. The analysis includes chloroplast DNA characters and morphological features. Results suggest at least two origins of heterostyly and one origin of cleistogamy, while corolla color appears to be quite plastic.
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1 - Cornell University, Plant Biology, 228 Plant Science Building, Ithaca, New York, 14850, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Wednesday, August 2nd, 2006
Time: 9:15 AM