E-Flora BC: Electronic Atlas of the Flora of British Columbia

Tiarella trifoliata var. unifoliata L. (Hook.) Kurtz
one-leaved foamflower (oneleaf foamflower)
Saxifragaceae (Saxifrage family)

Introduction to Vascular Plants

© Bryan Kelly-McArthur  Email the photographer   (Photo ID #70294)

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Distribution of Tiarella trifoliata var. unifoliata
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Species Information

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Perennial herb from scaly rhizomes; flowering stems 20-50 cm tall, with a few leaves, glandular-hairy above.
Basal leaves heart-shaped, 3-12 cm wide, about as long, simple and shallowly to deeply 3- to 5-lobed or compound with 3 stalked leaflets that are lobed or deeply cleft, almost to the base, toothed, hairy and usually glandular, the stalks longer than blades, stipules about 1 cm long; stem leaves similar to the basal, 2 or 3, reduced; stipules to 1 mm long.
Inflorescence a narrow, many-flowered, terminal cluster, up to 15 cm long, densely glandular-hairy; petals 3-4 mm long, thread-like; calyces bell-shaped, 1.5-2.5 mm long, glandular-hairy, hypanthium bell-shaped, free of ovary, lobed 1/2 to 2/3 length, lobes irregular, the upper lobe largest; stamens 10.
Capsules, borne horizontally, one valve 3-5 mm long, the other 7-10 mm long; seeds blackish, about 1.5 mm long, shining, nearly smooth.
Three infraspecific taxa have been recognized. These taxa are widely sympatric but var. trifoliata generally occurs at lower elevations (up to 650 m), while var. unifoliata generally occurs above 650 m. Variety laciniata is a hybrid between the latter two and occurs frequently on Vancouver Island and sporadically on the mainland.

1. Leaves simple, shallowly to deeply 3- to 5-lobed........... var. unifoliata (Hook.) Kurtz1.

1. Leaves compound, with 3 stalked leaflets.

2. Leaflets lobed............. var. trifoliata

2. Leaflets deeply cleft, almost to the base............. var. laciniata (Hook.) Wheelock

Source: The Illustrated Flora of British Columbia

Habitat / Range

Moist forests, meadows and streambanks in the lowland and montane to subalpine zones; common throughout BC south of 58degreeN; N to the Aleutian Islands and S AK, E to AB and S to MT, ID and CA.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Tiarella trifoliata var. unifoliata

The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)

Site Information
Value / Class




Elevation (metres) 0 1183 2750
Slope Gradient (%) 0 22 145
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
0 340 360
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
0 4 8
Modal Nutrient Regime
Number of field plots
 species was recorded in:
Modal BEC Zone Class
All BEC Zones (# of stations/zone) species was recorded in: BWBS(1), CDF(1), CWH(646), ESSF(2776), ICH(2563), IDF(85), MH(151), MS(284), PP(1), SBPS(4), SBS(586), SWB(1)


The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is not evaluated, unknown or variable.

Synonyms and Alternate Names

Tiarella trifoliata subsp. unifoliata (Hook.) Kern
Tiarella unifoliata Hook.

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References