Weed of the Week: Southwestern Cupgrass

Written by:  Garret Montgomery, Jason Bond, and Tom Eubank

Southwestern Cupgrass

Family: Poaceae
Scientific name: Eriochloa acuminata (J. Presl) Kunh
Synonyms: tapertip cupgrass, southern cupgrass

Southwestern cupgrass seed showing “cup” where seed attaches to panicle

Southwestern cupgrass is an erect, summer annual grass that can reach up to 4 feet in height but can also grow prostrate in areas where it is continually mowed.  Its ligule is a fringe of hairs.  The entire plant is usually hairless, and plants will have several tillers with stems sometimes rooting from the nodes.  Leaf blades of southwestern cupgrass are generally 1 to 10 inches long.  Seed are a distinguishing characteristic and resemble two seeds together.  Southwestern cupgrass is distinguished from other annual grasses such as browntop millet (Urochloa ramosa) by its lack of hairs and by the “cup” where seed attach to the panicle.

Southwestern cupgrass is native to North America and can be found throughout Mississippi in turf areas, roadsides, railroad beds, and also in agronomic fields.  Southwestern cupgrass has become an increasing problem in recent years in Mississippi, but it generally emerges with other grass species and can be controlled with most grass herbicides.

Bryson, C.T. and M.S. DeFelice. 2009. Weeds of the South. Athens, GA: University of Georgia Press. pp. 378.

Ligule as fringe of hairs

Seedhead of southwestern cupgrass