The many clematis species and hybrids are not as popular in America as they are in Great Britain and parts of Europe, yet if the plants shown at our great spring flower shows are a criterion, they certainly are not to be neglected here. About 230 species are widely distributed throughout the temperate regions of the world. One hundred species and hybrid varieties are being commercially grown in America and probably nearly twice that number are offered in Europe. One English nurseryman alone lists 130.
Clematis is native chiefly in the northern temperate regions of the world. Three of the American species are excellent garden plants and from Europe are likewise important, but in the following list it will be noted that to species and botanical varieties which are natives of Asia also make good ornamentals. It is the large-flowered hybrids which seem to capture the public fancy, and it is these which are forced for display purposes in the shows. There are of course herbaceous species as well as woody species.
Although the first man-made hybrid was probably made in 1830, it was not until about 1858 that the first large-flowered hybrid of C. lanziginosa originated (C. x jackmanii), and this started many an enthusiastic hybridizer in his efforts to obtain large-flowering varieties. Although a century has elapsed since growers first became interested in the hybrids, we do have fairly accurate records of where and when these originated. These vines are frequently not the easiest to grow properly. They need an alkaline or limestone soil, some shade, and frequently they respond well if in some way the lower parts of the stems are protected from breakage and mechanical injury. It is at this point that disease frequently enters the plants, and when injury does occur, disease enters and is often quickly followed by destruction of the plant.
The leaf stalks act as tendrils in clinging to supports. Clematis flowers have no true petals. It is the large, brilliant-colored sepals which are so interesting. Actually, some of those species and varieties with medium-sized to small flowers make the best general ornamentals. Clematis paniculata, C. montana rubens, C. texensis are all in this class, as is the variety ‘Huldine’ with 4 whitish sepals and an over-all dia. of about 4 in. A poorly grown plant of ‘Nellie Moser’ may have flowers only 4 in. across, whereas, one that is well grown would have flowers twice that size. Clematis climb by attaching their leaf stalks about the means of support. They have opposite, usually compound, leaves, with either solitary flowers or flowers in clusters.
The behavior of seed is variable. It may be stored dry in airtight containers in a cool place for up to a year and then processed. If in doubt concerning its behavior, stratify for 3 months at 40° F., then sow. Softwood cuttings usually root well, best taken from young shoots in the greenhouse in Jan. or Feb. Sometimes the large-flowered hybrids are grafted or layered, but own rooted plan always preferable to others.