Muhlenbergia arsenei
Tough muhly, Tough Muhly
Family: Poaceae · Type: Grass · Native
Conservation status: CNPS 2B.3
Muhlenbergia arsenei (Tough muhly) is a native California grass in the Poaceae family, recognized by limestone habitat and purple anthers distinctive.
Tough muhly is a rare (CNPS 2B.3) California native perennial found in the Clark Mountain Range in limestone rock outcrops and slopes at elevations of 1,400 to 1,860 meters. Flowering from August to September, this plant produces purple-tinged flowers in narrow inflorescences 4 to 12 centimeters long with loosely arranged branches. Growing with decumbent stems 15 to 40 centimeters tall, it forms tufts with occasional short rhizomes. Its narrow leaves are tightly rolled, less than 2 millimeters wide and 1 to 5 centimeters long, with distinctive ligules 1 to 2 millimeters long that have a large tooth on each side. The plant's delicate purple anthers and soft-hairy lemmas add to its distinctive appearance.
Identification and appearance
Key characters: 10 sympatric species; limestone habitat and purple anthers distinctive
Habitat and range
Habitat: Limestone rock outcrops, slopes
Elevation: 1400-1860 m
California counties: San Bernardino
Outside California: to southeastern Utah, northern New Mexico, northern Baja California
Bloom period
Muhlenbergia arsenei blooms Aug-Sep.
Conservation status
CNPS 2B.3
How to tell it apart
vs Cenchrus: Cenchrus has spiny burs enclosing seed clusters; Muhlenbergia has open panicles without spines.; vs Nassella: Nassella has prominent bent awns; Muhlenbergia awns are straight or absent.; vs Festuca: Festuca has multiple-flowered spikelets; Muhlenbergia typically has single-flowered spikelets in open panicles.; vs Carex: Carex (sedges) has triangular stems and separate male/female flowers; Muhlenbergia has round stems.; vs Juncus: Juncus (rushes) has tiny brown chaffy flowers in clusters; Muhlenbergia has typical grass spikelets.
Frequently asked questions
Is Muhlenbergia arsenei native to California?
Yes. Muhlenbergia arsenei is native to California (recorded as native).
When does Muhlenbergia arsenei bloom?
Muhlenbergia arsenei blooms Aug-Sep.
Where in California does Muhlenbergia arsenei grow?
Muhlenbergia arsenei occurs in San Bernardino, at elevations of 1400-1860 m.
What plant family does Muhlenbergia arsenei belong to?
Muhlenbergia arsenei is in the Poaceae family, genus Muhlenbergia.
Is Muhlenbergia arsenei rare or endangered?
Muhlenbergia arsenei carries California Rare Plant Rank 2B.3, 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.