Systematics Section / ASPT
Kennedy, Aaron H. , Watson, Linda E. .
Phylogenetic relationships within the myco-heterotrophic orchid genus Hexalectris Raf.
Seven species and two subspecies are recognized in the largely North American orchid genus Hexalectris. Its species are terrestrial, fully myco-heterotrophic, and have variously colored erect leafless stems that represent the aboveground portion of the plant. Flowers are variable in terms of their number, color, lateral sepal shape, petal shape, anther color, and number of lamellae. Its center of diversity is the mountainous regions of southern Texas and northern Mexico. All seven species are native to Mexico with five of these also occurring in the United States. Additionally, H. brevicaulis is endemic to Mexico and H. parviflora is native to Mexico and Guatemala. The most widespread taxon, H. spicata var. spicata, ranges from northern Mexico, north to Missouri, east to the Atlantic coast, and south into central Florida. The phylogenetic relationships among Hexalectris taxa are unclear. Previous authors (FNA included) have speculated based on floral morphology, that H. spicata s.l., H. revoluta s.l., H. nitida, and H. parviflora form a complex of closely related species. Additionally, the cleistogamous variety of H. spicata, var. arizonica, has been suggested to be a hybrid taxon formed from H. spicata var. spicata and H. nitida or H. revoluta. The phylogenetic placement of the remaining two species, H. warnockii and H. brevicaulis, remains unclear. To resolve phylogenetic relationships among Hexalectris species and to test its monophyly, we are utilizing DNA sequences of the internal transcribed spacers (ITS) of nrDNA.
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1 - Miami University, Department of Botany, 316 Pearson Hall, Oxford, Ohio, 45056, USA
Presentation Type: Poster
Location: Salon C, D & E - Gov Ballroom/Hilton
Date: Tuesday, August 16th, 2005
Time: 12:30 PM