Aristida oligantha
Oldfield three-awn
(c) Zihao Wang, some rights reserved (CC BY), uploaded by Zihao Wang · licence
Family: Poaceae · Type: Grass · Native
Aristida oligantha (Oldfield three-awn) is a native California grass in the Poaceae family, recognized by long glumes and spreading spikelets.
Oldfield three-awn is a California native annual grass found in northwestern California, the northern Sierra Nevada foothills, Central Valley, southern coastal ranges, and mountains of the Peninsular Ranges at elevations below 1,000 meters in disturbed places, dry slopes, grasslands, shrublands, and woodlands. Flowering from July to November, this plant produces pale tan to light brown spikelets with divergent, spreading seed heads 5 to 20 centimeters long. Growing with highly branched stems 30 to 60 centimeters tall, it develops intricate, open raceme-like clusters. Its narrow leaves are very slender, 3 to 15 centimeters long and typically less than 2 millimeters wide, often tightly inrolled. The distinctive seed heads feature delicate awns 10 to 70 millimeters long, spreading outward in an elegant, wispy arrangement.
Identification and appearance
Key characters: 3 sympatric species; distinguished by long glumes and spreading spikelets
Habitat and range
Habitat: Disturbed places, dry slopes, fields, grassland, shrubland, woodland
Elevation: < 1000 m
California counties: Amador, Butte, El Dorado, Humboldt, Merced, Sacramento, San Bernardino, Shasta, Siskiyou, Tuolumne, Yuba, Modoc, Monterey, Riverside, Solano, Stanislaus, Tehama, Sonoma, Placer, Del Norte, Calaveras, Nevada, Sutter, Mendocino, Madera, Lake, Fresno, San Joaquin, Imperial
Outside California: to Oregon, eastern United States
Bloom period
Aristida oligantha blooms Jul-Nov.
How to tell it apart
vs Muhlenbergia: Aristida always has three awns per seed; Muhlenbergia has one awn or none.; vs Hilaria: Aristida has three awns on each spikelet; Hilaria has spikelets grouped in threes with single awns.; vs Bromus: Aristida's three thin straight awns are unmistakable; Bromus has single awns and papery seed coverings.; vs Schismus: Aristida has three long awns per seed; Schismus is a tiny annual with no awns at all.; vs Stipa: Aristida has three straight awns; Stipa has one twisted, bent awn.
Frequently asked questions
Is Aristida oligantha native to California?
Yes. Aristida oligantha is native to California (recorded as native).
When does Aristida oligantha bloom?
Aristida oligantha blooms Jul-Nov.
Where in California does Aristida oligantha grow?
Aristida oligantha occurs in Amador, Butte, El Dorado, Humboldt, Merced, Sacramento, San Bernardino, Shasta and other counties, at elevations of < 1000 m.
What plant family does Aristida oligantha belong to?
Aristida oligantha is in the Poaceae family, genus Aristida.
What habitat does Aristida oligantha grow in?
Aristida oligantha grows in Disturbed places, dry slopes, fields, grassland, shrubland, woodland.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.