Woolly cupgrass

Encyclopedia Article

Woolly cupgrass          Eriochloa villosa (Thunb.) Kunth

Family: Poaceae                                             
Life cycle: Annual
Native status: Native to China
Habitat: Crop fields                                       

General description: Hairy ligule, leaves covered with very short, dense hairs (may need hand lens to see). Erect plants reaching heights of 3 to 4 ft. Branched inflorescence with individual spikes having two rows of seeds.

Key ID traits: Seedlings: large seed attached to root; short first leaf parallel to soil. Mature plants: leaves proportionally shorter than those of foxtails and come off of stem at more obtuse angle. Leaves covered with short dense hairs that often require hand lens to see. One margin of leaf often rippled. 

Similar species: Small seedlings of green foxtail have similar growth habit, but lack the large seed.

Miscellaneous: The name woolly cupgrass comes from the fringe of hairs surrounding ‘cup’ where seed are attached. Local lore states that the original infestation started on a farm outside of Creston where a Chinese circus touring the Midwest in the early 1900s had established a base camp. First identified in the 1950s in Iowa, it began to spread rapidly in corn and soybean fields in the 1980s as farmers relied more on herbicides and less on tillage for weed control. The large seed science of woolly cupgrass compared to the foxtails and other annual grasses makes it more tolerant to many preemergence herbicides.

seedlings have broad leaves
Woolly cupgrass seedlings have wide leaves compared to most other annual grasses, and the first leaf typically is parallel with the soil surface.


W. cupgrass leaves often have one margin with a rippled edge.


Woolly cupgrass (L) seed is 3-4X bigger than those of giant foxtail (R).  

Carefully removing seedlings from soil and finding the seed attached to the root is the simplest way to differentiate small woolly cupgrass from the more common foxtails.


seedheads have branches with two rows of seed
Seedheads have branches with two rows of seed