Developmental and Structural Section
Varassin, Isabela G. , Penneys, Darin S. , Michelangeli, Fabian A. .
Comparative anatomy and morphology of nectar-producing Melastomataceae.
Most Neotropical Melastomataceae have bee-pollinated flowers with poricidal anthers. However, in the Neotropics nectar is known to be produced in about 80 species in 8 genera from 4 different tribes. These nectar producing species are pollinated by both vertebrates (hummingbirds, bats and rodents), and invertebrates (bees and flies). We studied the overall floral morphology and anatomy of 14 species in 6 genera of nectar producing Melastomataceae (Blakea, Brachyotum, Charianthus, Huilaea, Meriania and Miconia). Anatomical methods included scanning electron microscopy, and serial sections of paraffin embedded flowers. Anatomical sections were studied under carbohydrate-specific, protein-specific and general stains. All the vertebrate pollinated flowers have petals that do not open completely at anthesis, forming a pseudo-tubular corolla, while closely related species that are bee pollinated have rotate corollas. In most species nectar secretion is related to stomatic or epidermal nectaries and not filament slits as previously reported. Moreover, the nectar is probably supplied by large vascular bundles near the release area. Blakea and Huilaea have stomatic nectaries located upon the dorsal anther connective appendages. Brachyotum also has stomatic nectaries on the anther connective, but these are distributed along most of the connective. Meriania may release nectar through the anther connective, but also has stomatic nectaries on the inner walls of the hypanthium. Miconia has stomatic nectaries on the ovary apex. Charianthus nectaries were not found, but there is circumstantial evidence that nectar release happens through the epidermis at the apex of the ovary and the lower portions of the inner wall of the hypanthium.
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1 - Universidade Tuiuti do Paraná, Curitiba, Parana, Brazil
2 - University of Florida, Department of Botany, 220 Bartram Hall, P.O. Box 118526, Gainesville, Florida, 32611-8526, USA
3 - 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: Boulevard C/Hilton
Date: Tuesday, July 10th, 2007
Time: 11:15 AM