Appearance

Achnatherum brachychaetum is a densely tufted perennial, with shallow roots and erect stems to 3.3 ft. (1 m) tall. Foliage is tough and unpalatable to livestock, except for young shoots. It is present almost year round. It is often associated with alfalfa fields. The dense clumps can mechanically interfere with mowing. 

Foliage

The leaf blades are linear, 0.04-0.07 in. (1-2 mm) wide, 16-24 in. (40-60 cm) long, flat or slightly involute, and rigid. Feels rough to touch. The sheaths are open and glabrous, but with ciliate hairs along the upper margins and especially at the auricles. The ligules are membranous. 

Flowers

Achnatherum brachychaetum flowers in the Spring and Summer. The panicles are nearly pyramidal 8-12 in. (20-30 cm) long and just pass the tops of the blades. Spikelets with 1 floret. The glumes are glabrous and nearly equal, ranging from 0.24-0.31 in. (6-8 mm) long. 

Fruit

The seed have many hairs. Awns are straight or bent and up to 0.8 in. (1.8 cm) long. Modified spikelets called cleistogenes can be found inside the stems above the nodes of flowering shoots and at the stem base. 

Ecological Threat

Achnatherum brachychaetum can be found in disturbed sites. It is often seen in alfalfa fields and nearby drainage ditches, dairies, and horse pastures. 

Citations

Winston, R.L., Andreas, J.E., Milan, J., DesCamp, W., Randell, C.B., and M. Schwarzlander. 2014. New Invaders of the Southwest. United States Department of Agriculture, Forest Health Technology Enterprise Team. FHTET-2014-12. Retrieved from https://bugwoodcloud.org/resource/files/14767.pdf

 

Selected Images

Maps

Invasive Listing Sources

• California Invasive Plant Council
• California Noxious Weeds
• New Invaders of the Southwest

References