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Systematics Section / ASPT

Finch, Courtney [1], Barber, Janet C. [1].

Evolution of Ornamentation and Flower Color in the Orchid Genus Thelymitra.

Thelymitra is an Australasian orchid genus comprising 60-70 species that possess a unique staminodal structure called a mitra. This structure varies in degree of ornamentation, shape and color; some have been described as resembling pom pons, tufts of hair or rabbit ears. About 75% of Thelymitra species have flowers of a brilliant deep blue, a color found in only five of the 800 described orchid genera. Although blue is predominant, Thelymitra flowers may also be pink, purple, white, yellow or multi-colored. Most orchids have a labellum that differs from the rest of the perianth in color, shape and size. In contrast, Thelymitra flowers are all one color or color pattern, and have a perianth symmetrical in size and shape. Thelymitra are floral mimics of flowers in the Liliaceae and Goodeniaceae, a feature characteristic of pollination by deceit. Despite this suite of unique features, Thelymitra remains understudied and taxonomic relationships within the genus have long been debated. Current hypotheses of relationships are based on morphological characters and an unpublished ITS phylogeny. In this study, I will use chloroplast DNA markers to reconstruct a phylogeny of 17 species of Thelymitra that exhibit color and mitra variation. Mitra character and flower color will be mapped onto the phylogeny for a preliminary assessment of evolution of ornamentation and color pattern in the genus.


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1 - Saint Louis University, Department of Biology, 3507 Laclede Avenue, St Louis, Missouri, 63103-2010, USA

Keywords:
Phylogeny
Orchidaceae
Thelymitra.

Presentation Type: Poster
Session: 33-81
Location: Salon C, D & E - Gov Ballroom/Hilton
Date: Tuesday, August 16th, 2005
Time: 12:30 PM
Abstract ID:56


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