Linnaeus named the Clematis genus in 1753.  
See also white Clematis

Foothills, montane. Woodlands.  Spring, early summer.
Shearer Creek Trail, May 17, 2006.

The large flowers of this Clematis do not mean that the plant is conspicuous, for the plant tends to twine along the ground, into low bushes, and up tree trunks in deep forest shade. Look for it near the bottom of moist mountainsides.  (The yellow flower and Holly-like leaves belong to Mahonia repens.)

Linnaeus named the Atragene genus in 1753, Thomas Nuttall named this species Atragene columbiana in 1834, Torrey and Gray renamed it Clematis columbiana in 1838, and Jens Hornemann (1770-1841) named it Atragene occidentalis.

"Atragene" is of unknown origin according to William Weber.

Foothills, montane. Woodlands.  Spring, early summer.
Taylor Creek Trail, June 2, 2004.

Foothills, montane, subalpine.  Meadows, woodlands.  Spring, early summer.
Mesa Verde National Park, Prater Ridge Trail, May 14, 2004.

Because it is uncommon and often grows in deep vegetation, Coriflora hirsutissima is easily overlooked. Once sighted, however, it is unmistakable and unmatchable.  Erect slim stems produce small, airy leaf clusters.  The stems are topped by a flanged, upside down flower bowl of deep, silvery purple. The silvery glisten to the flower is, as seen in the picture below, the result of a myriad of very fine hairs.  The flower gives way to a feathery swirl of seed pods that always attracts more attention than the flower.

Frederick Pursh named this species Clematis hirsutissima in 1814; William Weber created the Coriflora genus in 1996.

Hairs covering the flower and its stalk give rise to its species name: "hirsutissima", "hairy".  "Coriflora" is Greek for "leathery", referring to the texture of the flower.

Foothills, montane, subalpine.  Meadows, woodlands.  Spring, early summer.
Narraguinnep Natural Area, May 28, 2004.

Foothills, montane, subalpine.  Meadows, woodlands.  Spring, early summer.
Mesa Verde National Park, Prater Ridge Trail, June 3, 2004.

Feathery plumes that will help disperse the fertilized seeds bristle out from the ovary.

Foothills, montane, subalpine.  Meadows, woodlands.  Spring, early summer.
Mesa Verde National Park, Prater Ridge Trail, June 3, 2004.

See also white Clematis