Systematics Section / ASPT
Estes, Dwayne , Small, Randall , Wofford, Eugene .
Studies in the genus Gratiola section Nibora (Scrophulariaceae).
The genus Gratiola (Scrophulariaceae) contains ca. 25 species of annual or perennial wetland-adapted herbs that are distributed mostly throughout temperate zones. The center of diversity for the genus is in the southeastern United States where ten species occur. In the most recent treatment of the North American members of the genus, two sections of Gratiola were recognized, sect. Gratiola and sect. Nibora. Section Nibora is restricted to the Nearctic region and contains six species: G. ebracteata, G. flava, G. floridana, G. heterosepala, G. neglecta, and G. virginiana. One putative new species similar to the widespread G. neglecta was discovered while conducting fieldwork in the southeastern United States. Additional work indicates that a second species, G. gracilis, which has long been synonymized with G. neglecta, should be reinstated as a distinct species and taken out of synonymy with G. neglecta. To clarify relationships within sect. Nibora we will use both morphological and molecular characters. Preliminary morphological analysis has revealed consistent differences in leaf and flower morphology, seed size, pubescence, and habitat between the putative new species, G. gracilis, and other members of the section. In addition, a preliminary molecular study of representative taxa of sect. Nibora suggests that noncoding chloroplast DNA sequences will yield sufficient variation to resolve relationships within the section.
1 - University of Tennessee, Department of Botany, 437 Hesler Biology, Knoxville, Tennessee, 37996, USA
Presentation Type: Paper
Location: Cottonwood A (Snowbird Center)
Date: Tuesday, August 3rd, 2004
Time: 8:15 AM