ON THE TAXONOMIC STATUS OF ERIOGONUM ROBUSTUM (POLYGONACEAE), A RARE ENDEMIC IN WESTERN NEVADA

Evidence from the morphology, genetics, and biogeography of a rare end emic from western Nevada, Eriogonum robustum, is presented to determin e its most accurate taxonomic classification. Previous authors have cl assified E. robustum Greene both as a species and as a variety of E. l obbii Torrey & Gray. However, results of a morphometric comparison for 9 characters establish that significant morphological differentiation exists between E. robustum and E. lobbii. In addition, results of a g enetic study using protein electrophoresis indicate that genetic diffe rentiation may exist between these 2 taxa. Furthermore, the 2 taxa are geographically ecologically, and reproductively isolated. Finally, th e selective pressures that act on E. robustum in a narrowly restricted cold-desert environment are different from those that act on E. lobbi i in a subalpine environment. Thus, all available data support a speci es-level taxonomic classification for E. robustum.