Tropical Biology Section
Kriebel, Ricardo , Michelangeli, Fabian A. .
A survey of floral symmetry and herkogamy in the tribe Miconieae (Melastomataceae).
The tribe Miconieae (Melastomataceae) is composed of over 2000 species in 19 neotropical genera. The great majority of them have 4-5 merous diplostemonous flowers (although they can be up to 12-merous and pleiostemonous in Conostegia and some isolated species of Miconia, Tococa and Clidemia). Pollination studies have confirmed bees as pollinators which obtain the pollen reward through buzzing although other pollinators are suspected in some species. Flowers in the Miconieae always have a radially symmetric perianth, but some of them have secondary bilateral symmetry arising from differential organization of the stamens and the style, and their relative position. In addition, floral parts in the tribe vary in color combinations creating different visual patterns. Lastly the relative length of styles and anthers also vary among species but not so within species. Using photographs of live plants at anthesis in the field, we coded characters relative to petal color and position, stamen color, position, length, and inflection of the filament, and relative length, position and inflection of the style. In total we scored close to 300 species. Secondary bilateral symmetry can be achieved in many different ways depending on the relative position of the androecium and the position of the style. Herkogamy (spatial separation of anthers and stigma) is often associated with secondary bilateral symmetry, but can also be present in radially symmetric flowers due to differences in the relative size of anthers and style, or how anthers are spread at anthesis. Conversely, not all flowers with secondary bilateral symmetry are herkogamus as anthers and style might all be bent towards the same side of the flower. These results will be discussed in the context of a tribe wide phylogenetic analysis.
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1 - The New York Botanical Garden, Institute of Systematic Botany, 200th St. & Southern Blvd., Bronx, NY, 10458-5126, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 552A/Convention Center
Date: Monday, August 2nd, 2010
Time: 11:00 AM