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

Clematis occidentalis (Hornem.) DC.
purple virgin's-bower (blue clematis; Columbia bower; Columbia virgin's bower; western blue virginsbower)
Ranunculaceae (Buttercup family)

Introduction to Vascular Plants

© Curtis Bjork  Email the photographer   (Photo ID #16468)

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Distribution of Clematis occidentalis
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Clematis occidentalis var. grosseserrata

Species Information

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Perennial vine; stems climbing to 2 m high or trailing on the ground to 5 m long.
Opposite, long-stalked, firm, 3-parted, the leaflets short-stalked, lance egg-shaped to triangular, 2-11 cm long, thin, not lobed or occasionally 1- to 3-lobed, margins usually entire, occasionally shallow-toothed, hairy when young, becoming smooth, tips pointed; the stalks persisting, acting as tendrils.
Inflorescence of nodding or inclined, solitary flowers on long, erect stalks at ends of short branches from previous year's stems, rarely terminal on long shoots of current year's stems, the flowers bisexual; petals absent; sepals 4, usually becoming wide-spreading, violet-blue to pale blue, narrowly egg-shaped, 3-6 cm long, soft-hairy, tips sharp-pointed; stamens 20-50; pistils 40-175.
Achenes, elliptic, soft-hairy; beaks 3-5 cm long, feathery-hairy.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Mesic to dry rocky slopes, thickets, bluffs and open forests in the steppe to subalpine zones; frequent in S BC east of the Coast-Cascade Mountains, less frequent northward; E to SK and S to WA, ID and MT.

Source: The Illustrated Flora of British Columbia


Ecological Framework for Clematis occidentalis

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) 35 1093 2020
Slope Gradient (%) 0 35 220
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
0 336 360
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
1 3 6
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: BG(4), BWBS(17), CWH(2), ESSF(46), ICH(94), IDF(123), MS(126), PP(24), SBPS(4), SBS(118)

Taxonomic and Nomenclatural Links

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General References