Skip to main content

U.S. Forest Service

Plant of the Week

Clematis occidentalis var. occidentalis range map. Clematis occidentalis var. occidentalis range map. USDA PLANTS Database.

Clematis occidentalis var. occidentalis. Figure 1: The attractive purple/pink bell-shaped flower of the purple clematis.

Clematis occidentalis var. occidentalis flowers. Figure 2: Multiple flowers on a single vine of purple clematis can make the plant quite showy.

Clematis occidentalis var. occidentalis flowers. Figure 3: Leaves of the purple clematis are long stalked and three parted.

Purple clematis (Clematis occidentalis (Hornem.) DC. var. occidentalis)

By Mark Jaunzems

This plants scientific genus name, Clematis, comes from the ancient Greek word for a vine with “long, lithe branches” and the species name, occidentalis, refers to “western”. (Black and Judziewicz, 2009). Both names are appropriate ones as this vine can grow to over 3 meters in length and the plant grows primarily in the rocky soils and hilly habitats that are more common in the western portions of the U.S. and Canada. Three varieties of this plant are known and this variety is the one that occurs in the eastern U.S. where the habitats it requires are uncommon. In the eastern U.S., purple clematis is listed as Endangered in Illinois, Maryland, and Rhode Island; of Special Concern in Massachusetts, Maine, and Wisconsin; and Presumed Extirpated in Ohio. Two other varieties of this plant also occur, var. grosserrata that occurs only in western North America and var. dissecta that has been found in only two counties of central Washington State. (USDA Plants Database)

Purple clematis is a climbing perennial with a woody stem and has very showy flowers that are 1½-inches to 2-inches long and hang down in an attractive bell like shape (Figure 1). One large plant can support several vines and many clusters of flowers on each vine making it quite a showy plant (Figure 2). Purple clematis also blooms quite early in the growing season, usually about the time that common dandelions (Taraxicum officinale) are just starting to bloom, which can be from April to June depending on where in the range the plants are located as well as local weather conditions. The leaves are three parted and long stalked and occur all along the woody stem sometimes together with the clusters of flowers or by themselves (Figure 3). Vines with leaves only occur in shady situations, but in sunny locations, the plants can have dozens of flowers. The habitats where this plant can occur are listed as being "calcareous cliffs, rock ledges, talus slopes, gravelly embankments, rocky woods, and clearings" (Flora of North America, Volume 3. 1997).

The clematis genus is one that has been of horticultural interest for a long time. This species does have horticultural value. This may account for at least some of the rarity of the eastern variety of this species, as gardeners may be tempted to dig up and transplant a showy and early bloomer like this species. This practice should be discouraged both on ethical and on practical grounds. Plants that are transplanted from the wild often do not survive. In areas where it is listed as protected, the digging of plants is illegal.

For More Information