Sphenopholis is a small genus of annual and perennial grasses (family Poaceae, order Poales) native to North America and Hawaii, where they grow in a wide range of habitats from open prairies and disturbed ground to shaded wetlands. The genus is commonly known as wedgescales, a name that reflects the distinctive shape of the second glume, which is widened or wedge-shaped — a key diagnostic character that separates Sphenopholis from closely related genera such as Koeleria and Trisetum. Plants are typically slender, with flat or loosely rolled leaf blades, open or contracted panicles, and small spikelets bearing two florets. The genus comprises roughly seven to eight accepted species, all confined to the Western Hemisphere. The most widespread member, S. obtusata (prairie wedgescale), occurs across nearly the entire contiguous United States, southern Canada, Hawaii, Mexico, and Hispaniola. S. intermedia (slender wedgescale) is almost equally wide-ranging across Canada and the United States, while S. pensylvanica (swamp wedgescale) favors moist, wooded habitats in the eastern half of the country.
Etymology
The name Sphenopholis derives from the Greek sphenos (wedge) and pholis (scale), referring to the distinctive wedge-shaped second glume that characterizes the genus. The common name "wedgescales" translates the same concept into English.
Distribution
Sphenopholis is native to North America, occurring in nearly every Canadian province and territory (except Nunavut) and nearly every US state. S. obtusata extends further to Hawaii, Mexico, and Hispaniola, making it the most broadly distributed member of the genus.
Ecology
Species occupy a broad range of open and semi-shaded habitats including prairies, meadows, roadsides, forest edges, and wetland margins. S. pensylvanica is characteristically a swamp species, while S. obtusata thrives in disturbed and upland sites across the continent.
