Tiarella trifoliata var. unifoliata
Oneleaf foamflower
Photo: parent species Tiarella trifoliata · (c) Gavin Slater, some rights reserved (CC BY) · licence
Family: Saxifragaceae · Type: Herb · Native
Tiarella trifoliata var. unifoliata (Oneleaf foamflower) is a native California herb in the Saxifragaceae family.
Oneleaf foamflower is a California native perennial found in coastal and northern California regions including the North Coast, Klamath Ranges, and San Francisco Bay Area, growing on moist shady streambanks at elevations below 2,000 meters. Flowering from May to August, this plant produces delicate white flowers in small clusters with distinctive rounded, sharp-tipped petals. Growing with slender stems 15 to 30 centimeters tall, it spreads in loose, woodland patches. Its single large leaf is typically 9 to 12 centimeters wide, with deeply cut lobes and rounded teeth giving the foliage a distinctive, intricate appearance. The plant forms small, elegant colonies in cool, damp forest understories.
Identification and appearance
Key characters: 1 sympatric species; key differentiators are leaf size, division pattern, and tooth shape
Habitat and range
Habitat: Moist shady streambanks
Elevation: < 2000 m
California counties: Del Norte, Mendocino, Humboldt, Santa Cruz, Trinity, Sonoma, San Mateo, Siskiyou, Santa Clara, Monterey, San Benito, Placer
Outside California: to Alaska, eastern to Alberta, Montana
Bloom period
Tiarella trifoliata var. unifoliata blooms May-Aug.
How to tell it apart
vs Heuchera: Tiarella has white petals and a loose panicle; Heuchera has tiny greenish-pink petals and bell-shaped flowers.; vs Tellima: Tiarella petals are entire (smooth-edged); Tellima petals are deeply fringed into 5-7 narrow segments.; vs Vancouveria: Tiarella has simple flowers in clusters; Vancouveria has compound leaves with leaflets and nodding columbine-like flowers.; vs Boykinia: Tiarella has unequal fruit valves; Boykinia has equal fruit valves and saucer-shaped flowers.; vs Rubus: Tiarella has tiny white flowers in spikes; Rubus has larger rose-like flowers and compound leaves.
Frequently asked questions
Is Tiarella trifoliata var. unifoliata native to California?
Yes. Tiarella trifoliata var. unifoliata is native to California (recorded as native).
When does Tiarella trifoliata var. unifoliata bloom?
Tiarella trifoliata var. unifoliata blooms May-Aug.
Where in California does Tiarella trifoliata var. unifoliata grow?
Tiarella trifoliata var. unifoliata occurs in Del Norte, Mendocino, Humboldt, Santa Cruz, Trinity, Sonoma, San Mateo, Siskiyou and other counties, at elevations of < 2000 m.
What plant family does Tiarella trifoliata var. unifoliata belong to?
Tiarella trifoliata var. unifoliata is in the Saxifragaceae family, genus Tiarella.
What habitat does Tiarella trifoliata var. unifoliata grow in?
Tiarella trifoliata var. unifoliata grows in Moist shady streambanks.
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.