Schoenus nigricans
Black bog-rush
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Family: Cyperaceae · Type: Grass · Native
Conservation status: CNPS 2B.2
Schoenus nigricans (Black bog-rush) is a native California grass in the Cyperaceae family, recognized by Only Schoenus species in California, representing a primarily Old World genus with few New World populations.
Black bog-rush is a rare (CNPS 2B.2) California native perennial found in the San Gabriel Mountains, San Bernardno Mountains, and eastern Mojave Desert in marshes, swamps, and springs with alkaline soils at elevations below 1,500 meters. Flowering from August to September, this rush produces inconspicuous flowers with white-tinged fruits. Growing 20 to 70 centimeters tall with erect, wiry stems less than 1 millimeter in diameter, it has a distinctive spongy center with internal air cavities. Its leaves are narrow, less than 1 millimeter wide, with three-angled blades and dark black sheaths that split along the inner surface. The plant forms a caudex-like rhizome and produces small ovoid-ellipsoid fruits approximately 1 to 1.5 millimeters long.
Identification and appearance
Key characters: Only Schoenus species in California, representing a primarily Old World genus with few New World populations
Habitat and range
Habitat: Marshes, swamps, springs, generally alkaline soils
Elevation: < 1500 m
California counties: San Bernardino, Inyo
Outside California: Florida, Texas, to Mexico, Caribbean, Old World
Bloom period
Schoenus nigricans blooms Aug-Sep.
Conservation status
CNPS 2B.2
How to tell it apart
vs Juncus: Schoenus has blackish leaf sheaths and compact flower heads; Juncus has brown/green sheaths and open flower clusters.; vs Cyperus: Schoenus has blackened sheaths and rounded heads; Cyperus has green/brown sheaths and umbrella-like flat clusters.; vs Kyllinga: Schoenus has multiple sterile bracts at spike base; Kyllinga has only 2-3 bracts total per spike.; vs Dulichium: Schoenus flowers cluster at stem tip; Dulichium flowers emerge from leaf joints along the stem.
Frequently asked questions
Is Schoenus nigricans native to California?
Yes. Schoenus nigricans is native to California (recorded as native).
When does Schoenus nigricans bloom?
Schoenus nigricans blooms Aug-Sep.
Where in California does Schoenus nigricans grow?
Schoenus nigricans occurs in San Bernardino, Inyo, at elevations of < 1500 m.
What plant family does Schoenus nigricans belong to?
Schoenus nigricans is in the Cyperaceae family, genus Schoenus.
Is Schoenus nigricans rare or endangered?
Schoenus nigricans carries California Rare Plant Rank 2B.2, state rank S2.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CNPS Rare Plant Inventory · Index of California Plant Names · CalPhotos · CDFW CNDDB
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.