About Tridens flavus (L.) Hitchc.
Tridens flavus (L.) Hitchc. is a large, robust perennial bunchgrass, commonly known by the names purpletop, purpletop tridens, tall redtop, greasy grass, and grease grass. Its purple seeds inspire the common name purpletop, while its oily seeds give rise to the alternate common name "grease grass". This species reproduces both by seed and by tillers. It is frequently confused with the visually similar Johnson grass (Sorghum halepense), though the two are only distantly related. Tridens flavus can be easily distinguished from Johnson grass by its short, hairy ligule. It is native to eastern North America, where it is widespread across its native range. It most commonly grows in human-created habitats such as hay meadows and lawns. It acts as a larval host plant for four butterfly and moth species: the common wood nymph, crossline skipper, little glassywing, and Zabulon skipper.
