Tridens flavus
Purpletop Tridens, purpletop, redtop tridens, tall redtop tridens, redtop, tall redtop, greasegrass
Description: perennial grass
Place of origin: North America
Urban habitat: Commonly found in disturbed areas, along roadsides, railroads, abandoned fields; tolerant of road salt.
Ecological function: Food and habitat for insects and mammals.
History: Native to eastern and central North America, Tridens flavus has naturalized westward in the US and north into Canada. It has a history of use as feed for livestock. The seeds are oily leading to its common name greasegrass.