Clematis belongs to the Ranunculaceae family. This genus of climbers includes several very different species and varieties, flowering in different seasons so the flowers are more or less large, double, or otherwise. Certain species, like armandii, have persistent leaves. Clematis can reach 5 to 6 metres, the small-flowered species like montana can grow up to 10 metres. These are voluble vines which grow at a moderate rate and need to be grown with a dedicated support. They can be grown against walls, fences, grilles, pergolas, arches etc.