Trifolium howellii
Howell's clover, Howell's Clover
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Family: Fabaceae · Type: Herb · Native
Conservation status: CNPS 4.3
Trifolium howellii (Howell's clover) is a native California herb in the Fabaceae family, recognized by large leaflets and preference for wet, shaded habitats.
Howell's clover is a California native perennial found in northern Klamath Ranges, northern North Coast Ranges, and northern California Ranges in wet or shady meadows, sedge habitats, and alder swamps at elevations of 800 to 1,800 meters. Flowering from July to August, this plant produces green-white to pink flowers in compact heads 1.5 to 3 centimeters long, with blossoms eventually becoming reflexed. Growing robustly with erect glabrous stems, it reaches a substantial size with green stipules on mid-leaves measuring 1 to 2.5 centimeters long. Its leaves feature elliptic to ovate leaflets 4 to 10 centimeters in length, arranged along the stem with notable complexity. The plant produces a distinctive calyx 3.5 to 4.5 millimeters long with slender lobes nearly as long as its base tube.
Identification and appearance
Key characters: 50 sympatric species; large leaflets and preference for wet, shaded habitats
Habitat and range
Habitat: Wet or shady places, meadows with sedges, alder swamps
Elevation: 800-1800 m
California counties: Siskiyou, Humboldt, Del Norte, Trinity, Shasta
Outside California: Oregon
Bloom period
Trifolium howellii blooms Jul-Aug.
Conservation status
CNPS 4.3
How to tell it apart
vs Medicago: Trifolium flowers persist around fruits; Medicago flowers fall off leaving exposed coiled fruits.; vs Oxalis: Trifolium has pea-shaped flowers; wood-sorrels (Oxalis) have 5-petaled star-shaped flowers and heart-notched leaflets.; vs Melilotus: Trifolium flowers persist enclosing fruits; Melilotus flowers fall off leaving exposed ridged pods.; vs Castilleja: Trifolium has pea flowers and 3 toothed leaflets; paintbrush (Castilleja) has tubular flowers in colorful bracts.; vs Acmispon: Trifolium leaflets have toothed edges; Acmispon leaflets have smooth untoothed margins.
Frequently asked questions
Is Trifolium howellii native to California?
Yes. Trifolium howellii is native to California (recorded as native).
When does Trifolium howellii bloom?
Trifolium howellii blooms Jul-Aug.
Where in California does Trifolium howellii grow?
Trifolium howellii occurs in Siskiyou, Humboldt, Del Norte, Trinity, Shasta, at elevations of 800-1800 m.
What plant family does Trifolium howellii belong to?
Trifolium howellii is in the Fabaceae family, genus Trifolium.
Is Trifolium howellii rare or endangered?
Trifolium howellii carries California Rare Plant Rank 4.3, state rank S4.
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.