Flora of North America species comparison

Varieties 2 (2 in the flora).

At the beginning of the twentieth century, E. L. Greene described over a dozen species belonging to the Geum triflorum complex based on differences in leaf form and indument, the relative length and shape of the epicalyx bractlets and sepals, and petal length and shape. Most of these species were quickly reduced to synonymy by other botanists. When specimens are examined from across the continent, most of the characters used to separate species in the G. triflorum complex show nearly continuous variation. It seems best to treat these variants as belonging to one species. Whether and how to classify the variation within the species will remain controversial. Some character expressions correlate reasonably well with dividing the species into two varieties, as was first proposed by N. C. Fassett (1928). Variety triflorum occurs east of the Rocky Mountains and is typical of the grasslands covering the northern Great Plains; it also is the variety found in the mountains of Arizona and New Mexico. Variety ciliatum is common throughout the rest of the Rocky Mountains, the Sierra Nevada, and Cascade Range. Intermediate specimens occur here and there, particularly in Alberta and British Columbia.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Flowers of Geum glaciale have from five to nine petals with seven being the most common. Other species of Geum nearly always have five petals, which is standard in most rosaceous genera. The sepals of G. glaciale are usually in two whorls for a total of about ten, and the bractlets are in two to three whorls. The exact number of epicalyx bractlets and sepals is made difficult to determine by the thick covering of hairs and because individual sepals and bractlets are sometimes deeply divided into two equal lobes.

(Discussion copyrighted by Flora of North America; reprinted with permission.)