Clematis (from Ancient Greek klematis, a climbing plant, probably periwinkle) is a genus of mostly vigorous climbing lianas, with attractive flowers. Some species are shrubby, and some others are herbaceous perennial plants. They are generally calcicole species, found throughout the temperate regions of both hemispheres, and also in mountains in the tropics, on limestone and other basic soils. The cool temperate species are deciduous, but many of the warmer climate species are evergreen.
Most species are known as Clematis in English, while some are also known as traveller's joy, old man's beard, leather flower, vase vine and virgin's bower, the last three being names used for North American species.
One recent classification recognised 297 species of clematis. Unsurprisingly, therefore, modern taxonomists subdivide the genus. Magnus Johnson divided Clematis into 19 sections, several with subsections ; Christopher Grey-Wilson divided the genus into 9 subgenera, several with sections and subsections within them Several of the subdivisions are fairly consistent between different classifications, for example all Grey-Wilson's subgenera are used as sections by Johnson.
Subgenera of Clematis according to Grey-Wilson:
Although the genus Clematis is extremely diverse many of the most popular forms grown in gardens are cultivars belonging to the Viticella section of the subgenus Flammula as defined by Grey-Wilson. These larger flowered cultivars are often used within garden designs to climb archways, pergolas, wall-mounted trellis or to grow through companion plants. Raymond Evison chronicles the history and development of these forms which normally have large 12-15cm diameter upward facing flowers and believes they largely involve crosses of c. patens, c. lanuginosa and c. viticella.
Early season large flowering forms (e.g "Nelly Moser") tend towards the natural flowering habit of c. patens or c. lanuginosa while later flowering forms (eg. x jackmanii) are nearer in habit to c. viticella.
Clematis ligusticifolia is widespread across the western United States and grows in streamside thickets, wooded hillsides, and coniferous forests up to 4,000 feet. A related species, Clematis columbiana, is widespread from British Columbia south into Oregon, with a range that extends east into Montana and Wyoming. Clematis was referred to as "pepper vine" by early travelers and pioneers of the American West and used as a pepper substitute to spice up food during the period of western colonization, since during this period, Black pepper (Piper nigrum), was a costly and rarely obtainable spice.
The entire genus contains essential oils and compounds which are extremely irritating to the skin and mucous membrames. Unlike Black Pepper or Capsicum, however, the compounds in clematis cause internal bleeding of the digestive tract if ingested internally in large amounts. The plants are essentially toxic. Despite its toxicity, Native Americans used very small amounts of clematis as an effective treatment for migraine headaches and nervous disorders. It was also used as an effective treatment of skin infections.
A partial list of species: