Setaria adhaerens
Bur bristle grass
(c) Kevin Faccenda, some rights reserved (CC BY) · licence
Family: Poaceae · Type: Grass · Not Native
Setaria adhaerens (Bur bristle grass) is a non-native California grass in the Poaceae family, recognized by unique single bristle per spikelet distinguishes from all others.
Bur bristle grass is a naturalized annual grass found in the San Joaquin Valley and Coachella Valley in disturbed areas at elevations below 130 meters. Flowering from July to October, this plant produces pale green to tan bristled spikelets in compact clusters 2 to 6 centimeters long. Growing with slender stems 25 to 60 centimeters tall, it spreads readily in open ground. Its leaves are 5 to 10 millimeters wide, up to 10 centimeters long, with sparse hairs on the underside and a small ligule 1 to 2 millimeters long. The grass produces distinctive bur-like bristles, with one bristle emerging from each spikelet.
Identification and appearance
Key characters: 5 sympatric species; unique single bristle per spikelet distinguishes from all others
Habitat and range
Habitat: Disturbed areas
Elevation: < 130 m
Outside California: southern United States, Central America, widespread in subtrops
Bloom period
Setaria adhaerens blooms Jul-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 adhaerens native to California?
No. Setaria adhaerens is not native to California (recorded as not native).
When does Setaria adhaerens bloom?
Setaria adhaerens blooms Jul-Oct.
What plant family does Setaria adhaerens belong to?
Setaria adhaerens is in the Poaceae family, genus Setaria.
What habitat does Setaria adhaerens grow in?
Setaria adhaerens grows in Disturbed areas.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · 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.