The genus name is from Ancient Greek clématis, ("a climbing plant"). Over 250 species and cultivars are known, often named for their originators or particular characteristics.
Clematis is a genus of about 300 species within the buttercup family, Ranunculaceae. Their garden hybrids have been popular among gardeners, beginning with Clematis jackmanii, a garden standby since 1862; more hybrid cultivars are being produced constantly. They are mainly of Chinese and Japanese origin. Most species are known as clematis in English, while some are also known as traveller's joy, a name invented for the sole British native, C. vitalba, by the herbalist John Gerard; virgin's bower for C. terniflora, C. virginiana, and C. viticella; old man's beard, applied to several with prominent seedheads; leather flower for those with fleshy petals; or vase vine for the North American Clematis viorna.
The genus is composed of mostly vigorous, woody, climbing vines / lianas. The woody stems are quite fragile until several years old. Leaves are opposite and divided into leaflets and leafstalks that twist and curl around supporting structures to anchor the plant as it climbs. Some species are shrubby, while others, like C. recta, are herbaceous perennial plants. The cool temperate species are deciduous, but many of the warmer climate species are evergreen. They grow best in cool, moist, well-drained soil in full sun. Clematis species are mainly found throughout the temperate regions of the Northern Hemisphere, rarely in the tropics. Clematis leaves are food for the caterpillars of some Lepidoptera species, including the willow beauty (Peribatodes rhomboidaria). The timing and location of flowers varies; spring-blooming clematis flower on side shoots of the previous year's stems, summer/fall blooming clematis bloom only on the ends of new stems, and twice-flowering clematis do both.