There are 300 to 400 varieties in this class. [In The Gardener's Guide to Growing Clematis, Raymond Evison writes that 200 or so clematis species have been recorded...]

[From An Illustrated Encyclopedia of Clematis, p. 20:] By the time Moore and Jackman wrote The Clematis as a Garden Flower in 1872, about 230 Clematis species had been identified and scientifically recorded... By the year 2000, there were about 297 recorded species, of which at least 120 are native to China. About 150 species are in cultivation now.

[From Clematis For Everyone, p. 8:] there are over three hundred clematis species distributed throughout the world... many of the [species] have no, or at least little garden value, and are of interest only to the clematis collector, botanist or hybridist. However, their presence has given rise to the very splendid cultivars of today...

[From The Gardener's Guide to Growing Clematis, p. 7:] Most of the hardy gardenworthy species and their small-flowered hybrids can establish themselves quite easily [and] produce flowers for many years...

[Ibid, p. 9:] clematis species are native to many parts of the world... the majority of the species grown in European and North American gardens are natives of the northern hemisphere... the evergreen Australasians can be grown with care in milder gardens [and] are generally of botanical interest only, and are for use in heated conservatories... China boasts at least 108 species and they vary considerably from C. armandii [to] C. florida [to] the most important species of all, C. patens...

[Ibid, p. 10:] Generally the small-flowered species have fine fibrous rootlets... making the job of replanting established plants extremely difficult...