Skip to main content

How to Identify Purpletop

Purpletop, Tridens flavus, is a native, warm season grass that can be found in savannahs, fields, and roadsides, and grows three to five feet tall. Its stems, rachis, and spikelets are covered in a thin layer of an oily substance, leading to its other common name of Grease Grass. At the top of the leaf sheath, seen here under the blade, you can find short tufts of hairs. Pulling back the leaf blade reveals Purpletop's short hairy ligule.

Purpletop flowers in the summer, producing a panicle inflorescence that is up to one foot in size and open and airy. The branches of Purpletop droop at their tips, and of course the spikelets are purple in color.

This video is part of the Grasses at a Glance series by Natural Resources, Environment, and Energy Educator Erin Garrett, University of Illinois Extension. Explore the playlist. Read our blog, Grasses at a Glance.