Developmental and Structural Section
Cohen, Jim , Litt, Amy , Stevenson, Dennis Wm. .
The World of Walled Marriages: Comparative Floral Development in Lithospermum.
Lithospermum L. (Boraginaceae) comprises approximately forty species in both the Old and New Worlds, with a center of diversity in the southwestern United States and Mexico. Using cpDNA regions and morphological characters, a phylogeny of Lithospermum and related taxa was reconstructed. Lithospermum and related New World members of the Lithospermeae are a monophyletic group, with Macromeria D. Don, Onosmodium Michx., Nomosa I. M. Johnst. and Psilolaemus I. M. Johnst. nested within Lithospermum. Within this monophyletic group, heterostyly has either arisen three times or been lost multiple times. Floral development of one species from each of the three heterostylous clades has been examined in order to determine whether the developmental processes among the clades are similar or not. In the species examined, the style is arrested early in development in the short-style morph but continues to elongate in the long-style morph. Differences in style cell length, and not the number of cells, account for the difference in the lengths of the mature styles between the two morphs. The corolla tube of the short-style morph elongates at a faster rate than that of the long-style morph. Differences in cell number and initial point of filament attachment to the corolla account for the different anther heights between the two morphs. Although the developmental patterns in style and corolla tube elongation have each been described in separate distylous taxa, Lithospermum is the first genus in which these developmental patterns have been observed in the same taxon.
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1 - Cornell University, Plant Biology, 412 Mann Library, Ithaca, NY, 14853, USA
2 - The New York Botanical Garden, 200th St and Southern Boulevard, Bronx, NY, 10458-5126, USA
3 - New York Botanical Garden, Institute of Systematic Botany, 200Th Street & Southern Boulevard, Bronx, New York, 10458-5126, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, July 29th, 2008
Time: 10:00 AM