Atragene grosseserrata Rydberg, Bull. Torrey Bot. Club 29: 156. 1902; Clematis occidentalis subsp. grosseserrata (Rydberg) R. L. Taylor & McBryde

Stems ± viny, climbing or trailing, 0.25-2.5 m. Leaves: leaflets unlobed or occasionally 1-3-lobed, 2-11 cm, margins entire or less often shallowly crenate-serrate. Flowers: sepals often eventually wide-spreading, violet-blue to pale blue or rarely white, lance-ovate, 3-6 cm, margins often ± fluted, tips acuminate. 2 n = 16.

Flowering spring-early summer. Often deep, fine soils in shady forest, also cliffs and other rocky sites in open woods and thickets; 400-2800 m; Alta., B.C., Sask., Yukon; Colo., Idaho, Mont., Oreg., Utah, Wash., Wyo.

The names Clematis columbiana (Nuttall) Torrey & A. Gray and C. verticillaris var. columbiana (Nuttall) A. Gray have long and frequently been misapplied to this taxon. This erroneous usage continues in some horticultural references.