Setaria pumila subsp. pumila
Yellow bristle grass, Yellow Bristle Grass
Family: Poaceae · Type: Grass · Not Native
Setaria pumila subsp. pumila (Yellow bristle grass) is a non-native California grass in the Poaceae family, recognized by most widespread distribution but lacks strongly diagnostic features.
Yellow bristle grass is a naturalized annual found in western Klamath Ranges, northern Coast Ranges, California Rocky Formations, northern and central Sierra Nevada, southern Sierra Nevada foothills, Central Valley, San Francisco Bay Area, southern Coast Ranges, southern California, San Bernardino Mountains, Peninsular Ranges, eastern Sierra Nevada, and southwestern Mojave Desert at elevations below 1,680 meters in moist sites and disturbed areas. Flowering from June to October, this plant produces pale yellow to green-tinged flowers in dense, bristly spikes 2 to 6 centimeters long. Growing with erect stems 20 to 130 centimeters tall, it spreads quickly in open, disturbed landscapes. Its leaves are long and narrow, 5 to 30 centimeters in length and 3 to 10 millimeters wide, with smooth upper surfaces and short, barely noticeable ligules. The plant's distinctive bristly flower clusters feature 4 to 12 stiff bristles surrounding each small, greenish-yellow spikelet.
Identification and appearance
Key characters: 6 sympatric species; most widespread distribution but lacks strongly diagnostic features
Habitat and range
Habitat: Generally moist sites, disturbed areas, streambanks
Elevation: < 1680 m
California counties: Alameda, Marin, Butte, Tehama, Yolo, San Diego, Sutter, Mariposa, Fresno
Outside California: to southern Canada, eastern United States, Mexico, native to Europe
Bloom period
Setaria pumila subsp. pumila blooms Jun-Oct.
How to tell it apart
vs Cenchrus: Setaria bristles stay attached to the axis after the spikelet falls; Cenchrus bristles fuse into a spiny bur that drops with the seed.; vs Pennisetum: Setaria bristles are free and persistent below each spikelet; Pennisetum bristles form a deciduous involucre that falls as a unit with the spikelet.; vs Alopecurus: Setaria has stiff bare bristles subtending naked spikelets; Alopecurus has no bristles and its soft spikelets bear a bent awn from the lemma back.; vs Polypogon: Setaria's bristles are separate sterile branchlets left behind on the axis; in Polypogon the bristly look comes from awns on the glumes and the whole spikelet sheds.; vs Phleum: Setaria's cylindric head has projecting bristles between the spikelets; Phleum's dense spike is bristle-free with stiff, short-awned, keeled glumes.
Frequently asked questions
Is Setaria pumila subsp. pumila native to California?
No. Setaria pumila subsp. pumila is not native to California (recorded as not native).
When does Setaria pumila subsp. pumila bloom?
Setaria pumila subsp. pumila blooms Jun-Oct.
Where in California does Setaria pumila subsp. pumila grow?
Setaria pumila subsp. pumila occurs in Alameda, Marin, Butte, Tehama, Yolo, San Diego, Sutter, Mariposa and other counties, at elevations of < 1680 m.
What plant family does Setaria pumila subsp. pumila belong to?
Setaria pumila subsp. pumila is in the Poaceae family, genus Setaria.
What habitat does Setaria pumila subsp. pumila grow in?
Setaria pumila subsp. pumila grows in Generally moist sites, disturbed areas, streambanks.
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.