Any plant of the large genus Clematis, widely distributed herbs or vines of the family Ranunculaceae, buttercup family, many of them native to the United States. Some have an irritating sap. The vines, climbing by tendrils that are modified leafstalks, are the more popular and are usually profuse bloomers.

The flowers are varied in shape and color; the fruits are small and dry, with a feathery appearance. Most popular in North America are the Jackman clematis, C. jackmanii, a large purple hybrid, and the Japanese clematis Clematis stans with small white or blue flowers.