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COSEWIC Assessment and Update Status Report on the Scouler’s Corydalis in Canada


Global Range

Scouler’s corydalis is restricted to the Pacific Northwest in North America. It occurs west of the Cascades Mountains (mostly coastal) from north-western Oregon northward through Washington’s Olympic Peninsula to south-western Vancouver Island (Figure 3; Ownbey 1947; Hitchcock et al. 1969; Douglas et al. 1999a, 2000).

Figure 3: North American Range of Scouler’s Corydalis

Figure 3: North American range of Scouler’s corydalis.

Canadian Range

In Canada, Scouler’s corydalis is found only in south-western British Columbia. Known sites are limited to the Carmanah Creek, Cowichan Lake, Klanawa River and Nitinat River drainages (Figure 4; Douglas et al. 1999a). The extent of Scouler’s corydalis occurrence in Canada encompasses approximately 275 km2. However, due to limited road access to potential habitat for this species, a significant area of potential habitat remains unsearched at this time. The estimated further potential extent of Scouler’s corydalis occurrence is an additional 825 km2 if potential habitat in the Walbran and Cowichan Lake drainages is considered.

Figure 4: Scouler’s Corydalis Sites in British Columbia

Figure 4: Scouler’s corydalis sites in British Columbia.

Refer to Table 2 for population sizes within each of the drainage areas).

The south-western British Columbia occurrence of Scouler’s corydalis is about 80 km north of the Washington locations on the Olympic Peninsula. The Canadian range currently makes up approximately nine percent of the species’ total North American range.