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

Thalictrum occidentale A. Gray
western meadowrue (western meadow-rue)
Ranunculaceae (Buttercup family)

Introduction to Vascular Plants

© Heinz Baum  Email the photographer   (Photo ID #6168)

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Distribution of Thalictrum occidentale
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Species Information

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General:
Dioecious perennial herb from creeping, scaly rhizome and thin and fibrous roots; stems erect, 30-100 cm tall, simple or branched, smooth.
Leaves:
Mostly stem leaves, alternate, with flaring stipular sheaths, the basal and stem leaves stalked, 3- to 4-times 3-parted, the leaflets smooth to glandular, circular to egg- or wedge-shaped or heart-shaped, 10-30 mm wide, tips 3-lobed, the lobe margins round-toothed.
Flowers:
Inflorescence a many-flowered, open, terminal panicle, the lower bracts like reduced leaves, the upper small, simple; flowers unisexual, male and female flowers on separate plants; flower stalks about equal in length; petals absent; sepals usually 4 (-6), greenish-whitish to purplish-tinged, egg-shaped, 3.5-4.5 mm long in male flowers, 1.5-2 mm long in female flowers; stamens 15-30, the filaments purplish, threadlike, 4-10 mm long, the anthers 1.5-4 mm long, sharp-pointed; stigmas often purplish.
Fruits:
Achenes, 6-9, spreading to bent back, spindle-shaped, 6-9 mm long, glandular, strongly 3-veined on each side, stalks 0.4-1.2 mm long; beaks 3-4.5 mm long.
Notes:
A highly variable species, without sufficiently differentiated phases.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Moist to mesic meadows, thickets, clearings and open forests from the lowland to subalpine zones; common throughout BC except Queen Charlotte Islands, N Vancouver Island and the adjacent coast; N to SE AK, YT and NT, E to SK and S to CO, UT and N CA.

Source: The Illustrated Flora of British Columbia

Ecology

Ecological Framework for Thalictrum occidentale

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

Minimum

Average

Maximum

Elevation (metres) 0 1286 2750
Slope Gradient (%) -2 22 230
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
0 174 360
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
0 4 8
Modal Nutrient Regime
Class
C
Number of field plots
 species was recorded in:
5146
Modal BEC Zone Class
ESSF
All BEC Zones (# of stations/zone) species was recorded in: AT(39), BAFA(9), BG(2), BWBS(191), CDF(2), CMA(2), CWH(44), ESSF(1801), ICH(533), IDF(441), IMA(2), MH(3), MS(679), PP(16), SBPS(113), SBS(925), SWB(61)

Ecological Indicator Information

A shade-tolerant/intolerant, submontane to subalpine, Western North American forb distributed equally in the Pacific and Cordilleran regions, and marginally in the Central region. Occurs on fresh to very moist, nitrogen-rich soils within montane boreal, temperate, and cool mesothermal climates; its occurrence decreases with increasing elevation and latitude. Common and often plentiful in the herbaceous understory of open­canopy forests on water-shedding and water-receiving sites; occasionally inhabits exposed mineral soils on disturbed sites; tolerates fluctuating groundwater tables. Often associated with Athyriumfilix-femina, Cornus sericea, Gymnocarpium dryopteris, Lonicera involucrata, Oplopanax horridus, Ribes lacustre, and Tiarella trifoliata. A nitrophytic species characteristic of Moder and Mull humus forms.

SourceIndicator Plants of Coastal British Columbia (Information applies to coastal locations only)

Climate

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

Thalictrum occidentale var. breitungii
Thalictrum occidentale var. macounii B. Boivin
Thalictrum occidentale var. occidentale A. Gray

Taxonomic and Nomenclatural Links

Additional Photo Sources

Related Databases

General References