6b. Clematis Subg. Viticella Keener & W. M. Dennis, Taxon. 31: 42. 1982.
Viticella Moench, Methodus, 296. 1794
Woody vines . Leaf blade [simple] 1-2-pinnate, lobed or few-lobed, margins entire. Inflorescences axillary, on suppressed shoots from previous year's stems, 2-3-flowered bracteate fascicles or cymes, or flowers solitary, peduncle bracteate. Flowers bisexual, slightly or not nodding; sepals usually wide-spreading, not connivent, blue, violet, or rose violet [rarely white], broadly obovate to elliptic-rhombic, thin; filaments flattened but slender, glabrous or sparsely pubescent; staminodes absent. Achenes flattened; beak usually less than 1.5 cm, glabrous or silky.
Species 6 (1 in the flora): temperate regions, North America, Eurasia.
Clematis subg. Viticella has sometimes been included in Clematis subg. Viorna , as suggested by F. B. Essig (1992), although it is very different from subg. Viorna in the strict sense in the aspect of its flowers and was treated as a distinct genus by earlier authors.
Several other large-flowered European and Asiatic species and hybrids, including Clematis campaniflora Brotero, with broadly campanulate perianth, and C. florida Thunberg, C. lanuginosa Lindley, and C . × jackmanii T. Moore (= C. lanuginosa × C. viticella ), with rotate perianth often with 6-8 sepals, occasionally persist after cultivation; in some cases they have become very locally naturalized.