Isoetes howellii
Howell's quillwort
(c) Timothy McNitt, some rights reserved (CC BY), uploaded by Timothy McNitt · licence
Family: Isoetaceae · Type: Grass · Native
Isoetes howellii (Howell's quillwort) is a native California grass in the Isoetaceae family, recognized by amphibious habitat, lower elevation, and brownish-black leaf bases.
Howell's quillwort is a California native perennial found in the Klamath Ranges, Northern California Coast Ranges, Cascade Range, Sierra Nevada Foothills, northern Sierra Nevada, Central Valley, Central Coast, San Francisco Bay Area, Southern Coast Ranges, Southern California, and Peninsular Ranges in vernal pools and lake margins at elevations generally below 1,500 meters. As a distinctive aquatic plant, it produces bright green leaves that become terrestrial as they mature. Growing with rigid, deciduous leaves less than 30 centimeters long, the plant has a characteristic appearance with leaves that taper to a point and have a base ranging from brown to black. Its leaves are notably stiff and bright green, creating a distinctive quill-like structure in wet habitats. The sporangia membrane partially covers the reproductive structures, with male spores measuring 0.025 to 0.035 millimeters and female spores ranging from 0.3 to 0.5 millimeters with a ridged texture.
Identification and appearance
Key characters: 5 sympatric species - key features are amphibious habitat, lower elevation, and brownish-black leaf bases
Habitat and range
Habitat: Vernal pools, lake margins
Elevation: generally < 1500(2900) m
California counties: San Luis Obispo, San Diego, Riverside, Santa Clara, Sonoma, Shasta, Tehama, San Mateo, Siskiyou, Plumas, Tuolumne, Ventura, Butte, Del Norte, El Dorado, Fresno, Humboldt, Lake, Marin, Merced, Modoc, Monterey, Placer, San Bernardino, Madera, Sutter, San Benito, Trinity, Amador, Napa, Mendocino, Sacramento, Sierra, Lassen, Contra Costa, Stanislaus, Santa Barbara, Calaveras, Solano, Mariposa
Outside California: to Washington, Montana, Utah
How to tell it apart
vs Juncus: Isoetes has a bulbous corm-like base with embedded spore capsules; Juncus has fibrous roots without sporangia.; vs Subularia: Isoetes leaves arise from a bulbous base; Subularia has a thin taproot with small white flowers above the leaves.; vs Triglochin: Isoetes has spore capsules at leaf bases; Triglochin produces tall flower spikes with tiny greenish flowers.; vs Sparganium: Isoetes forms tight tufts from a corm; Sparganium has creeping stems and round, burr-like flower heads.; vs Pilularia: Isoetes leaves stand rigidly erect; Pilularia leaves coil in fiddlehead fashion when young.
Frequently asked questions
Is Isoetes howellii native to California?
Yes. Isoetes howellii is native to California (recorded as native).
Where in California does Isoetes howellii grow?
Isoetes howellii occurs in San Luis Obispo, San Diego, Riverside, Santa Clara, Sonoma, Shasta, Tehama, San Mateo and other counties, at elevations of generally < 1500(2900) m.
What plant family does Isoetes howellii belong to?
Isoetes howellii is in the Isoetaceae family, genus Isoetes.
What habitat does Isoetes howellii grow in?
Isoetes howellii grows in Vernal pools, lake margins.
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.