Approximately 250 species of wild buckwheat (Eriogonum spp.) are found in the world, with most of the species occurring in arid regions of the western United States. The group has undergone rapid evolution, leading to numerous closely related taxa. The sulfur buckwheats (Eriogonum umbellatum), of which there are 41 recognized varieties in the West, exemplify this rapid speciation. The Firehole River drainage is the only place where the variety endemic to the park, Yellowstone sulfur buckwheat (Eriogonum umbellatum var. cladophorum), is found.

Updated 11/16/2010