Oxalis trilliifolia
Three leaf woodsorrel
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Family: Oxalidaceae · Type: Herb · Native
Oxalis trilliifolia (Three leaf woodsorrel) is a native California herb in the Oxalidaceae family, recognized by umbellate white flowers and linear fruits diagnostic.
Three leaf woodsorrel is a California native perennial found in northern coastal, Klamath Ranges, and northern coastal ranges in dense conifer forest at elevations below 1,900 meters. Flowering from May to August, this plant produces delicate white to pale pink flowers in small umbel-like clusters with 3 to 9 blossoms. Growing from a creeping, fleshy, scaly rhizome with essentially no visible stem, it forms distinctive clusters of leaves at the rhizome tips. Its leaves have three leaflets less than 4 centimeters long, carried on hairy petioles up to 30 centimeters in length. The plant produces linear fruits less than 3 centimeters long, complementing its understated woodland presence.
Identification and appearance
Key characters: 7 sympatric species; umbellate white flowers and linear fruits diagnostic
Habitat and range
Habitat: Dense conifer forest
Elevation: < 1900 m
Outside California: to Washington
Bloom period
Oxalis trilliifolia blooms May-Aug.
How to tell it apart
vs Trifolium: Oxalis has heart-notched leaflet tips; clover has oval or elongate leaflet tips without notches.; vs Medicago: Oxalis leaflets fold at night and have notched tips; medick leaflets don't fold and have toothed edges.; vs Marsilea: Oxalis is a land plant with flowers; water clover is aquatic with spore-bearing structures.; vs Pelargonium: Oxalis is soft-stemmed with 3 leaflets; geranium is woody-based with palmately lobed leaves.; vs Bowlesia: Oxalis has clover-like leaves with 3 leaflets; Bowlesia has kidney-shaped undivided leaves.
Frequently asked questions
Is Oxalis trilliifolia native to California?
Yes. Oxalis trilliifolia is native to California (recorded as native).
When does Oxalis trilliifolia bloom?
Oxalis trilliifolia blooms May-Aug.
What plant family does Oxalis trilliifolia belong to?
Oxalis trilliifolia is in the Oxalidaceae family, genus Oxalis.
What habitat does Oxalis trilliifolia grow in?
Oxalis trilliifolia grows in Dense conifer forest.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · 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.