Schoenoplectus mucronatus
Rough-seed bulrush, rice-field bulrush, Rice-Field Bulrush
(c) John Tann, some rights reserved (CC BY) · licence
Family: Cyperaceae · Type: Grass · Not Native
Schoenoplectus mucronatus (Rough-seed bulrush) is a non-native California grass in the Cyperaceae family, recognized by small size, no leaf blades, and ridged black fruits.
Rough-seed bulrush is a naturalized perennial herb found in northern California regions including the North Coast Ranges, Sacramento Valley, San Francisco Bay Area, and Southern California coastal areas in fresh ponds and rice fields at elevations of 20 to 400 meters. Flowering from summer to fall, this plant produces small spikelets 7 to 12 millimeters long with subtle flower bracts. Growing with robust stems 40 to 100 centimeters tall, it has sharp three-sided stems approximately 2 to 3 millimeters in diameter. Its unique stem structure lacks leaf blades, instead featuring sheath-like bases that do not split, with spreading inflorescence bracts 1 to 10 centimeters long. The fruit is distinctive, featuring many wavy transverse ridges and generally appearing black, with small fruits 1.7 to 2.2 millimeters long.
Identification and appearance
Key characters: 8 sympatric species; distinguished by small size, no leaf blades, and ridged black fruits
Habitat and range
Habitat: Uncommon. Fresh ponds, rice fields
Elevation: 20-400 m
California counties: Butte, Tehama, Sonoma, Santa Barbara, Yuba, Humboldt, Glenn, Colusa, Sutter
Outside California: east-central United States, Eurasia, Africa, Australia
Bloom period
Schoenoplectus mucronatus blooms Summer-fall.
How to tell it apart
vs Juncus: Schoenoplectus has flowers in spikelets with overlapping scales; Juncus has separate flowers with 6 perianth parts.; vs Typha: Schoenoplectus has small spikelets of tiny flowers; Typha has dense brown cylindrical flower spikes (cattails).; vs Bolboschoenus: Schoenoplectus has smooth flower scales; Bolboschoenus scales are fuzzy-hairy.; vs Carex: Schoenoplectus has bisexual flowers in open spikelets; Carex has separate male/female flowers in enclosed sacs.; vs Scirpus: Schoenoplectus has dull bracts with notched tips; Scirpus bracts are pointed and often reddish-tinged.
Frequently asked questions
Is Schoenoplectus mucronatus native to California?
No. Schoenoplectus mucronatus is not native to California (recorded as not native).
When does Schoenoplectus mucronatus bloom?
Schoenoplectus mucronatus blooms Summer-fall.
Where in California does Schoenoplectus mucronatus grow?
Schoenoplectus mucronatus occurs in Butte, Tehama, Sonoma, Santa Barbara, Yuba, Humboldt, Glenn, Colusa and other counties, at elevations of 20-400 m.
What plant family does Schoenoplectus mucronatus belong to?
Schoenoplectus mucronatus is in the Cyperaceae family, genus Schoenoplectus.
What habitat does Schoenoplectus mucronatus grow in?
Schoenoplectus mucronatus grows in Uncommon. Fresh ponds, rice fields.
Related species
Other California species in the same genus, family, or bioregion.
- Schoenoplectus pungens var. longispicatus — Common three-square bulrush
- Schoenoplectus saximontanus — Rocky mountain bulrush
- Schoenoplectus sp. — Naked-stemmed bulrushes
- Schoenoplectus subterminalis — Water bulrush
- Schoenoplectus tabernaemontani — Soft-stem bulrush
- Schoenoplectus triqueter — Three-sided bulrush
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.