Developmental and Structural Section
Altamira, Wualu , Cohen, Jim .
Comparative Floral Development in Lithospermum.
The genus Lithospermum (Boraginaceae) includes species with very unique floral characteristics, such as heterostyly, cleistogamy, and flowers with long corollas and exserted anthers and stigmas. This last type of floral form (termed Macromeria-typeflowers) originated within the genus multiple times, and evidence suggests that hummingbirds and moths pollinate these flowers. In order to investigate whether plants that independently evolved this type of floral morphology follow similar or different patterns of development, floral developmental patterns were examined in two species with Macromeria-type flowers, Lithospermum macromeria and Lithospermum exsertum, and two related species, Lithospermum helleri and Lithospermum trinervium, that develop flowers with long corolla tubes and exserted stigmas, but with included anthers. Using light microscopy, the heights and lengths of various floral organs were measured and compared. Results indicate that in all four species the style elongates at a faster rate than the stamens; however, the development of anther height differs among the species. In the species with Macromeria-type flowers, the stamens continue to elongate throughout development, but the contribution of filament length and the point of attachment of the filaments to the corolla tube varies depending on the species. In L. trinervium and L. helleri, the anthers reach a maximum height approximately halfway through development, even though the style continues to elongate.
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1 - Texas A&M International University
2 - 7614 Laguna Del Mar Ct., Apt. 214, Laredo, TX, 78041, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Union D/Hyatt
Date: Monday, July 9th, 2012
Time: 1:30 PM