Editing Clematis (section)

===Subdivisions===
One recent classification{{which|date=September 2020}} recognised 297 species of clematis. Consequently, [[taxonomist]]s and gardeners subdivide the genus. Several classification systems exist.

Magnus Johnson divided ''Clematis'' into 19 [[section (botany)|sections]], several with subsections.<ref>{{cite book |last=Johnson |first=Magnus |title=The Genus Clematis |publisher=Magnus Johnson Plantskola AB |year=2001}}</ref> Christopher Grey-Wilson divided the genus into 9 [[subgenus|subgenera]] (''[[Clematis (subgenus)|Clematis]], [[Cheiropsis]], Flammula, [[Archiclematis]], [[Campanella (subgenus)|Campanella]], [[Atragene]], [[Tubulosae]], [[Pseudanemone]], [[Viorna]]''), several with sections and subsections within them.<ref>{{cite book |last=Grey-Wilson |first=Christopher |title=Clematis: The Genus: A Comprehensive Guide for Gardeners, Horticulturists and Botanists |publisher=Timber Press |year=2000}}</ref> Several of the subdivisions are fairly consistent between these two systems; for example, all of Grey-Wilson's subgenera are used as sections by Johnson. Alternatively, John Howell defined twelve groups: the Evergreen, Alpina, Macropetala, Montana, Rockery, Early Large-Flowered, Late Large-Flowered, Herbaceous, Viticella, Texensis, Orientalis, and Late Mixed groups.

Many of the most popular garden forms 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, [[pergola]]s, or wall-mounted [[Trellis (architecture)|trellises]], or to grow through companion plants. These forms normally have large 12–15&nbsp;cm diameter upward-facing flowers and are believed to involve crosses of ''C. patens'', ''C. lanuginosa'', and ''C. viticella''.<ref>{{cite book |last=Evison |first=Raymond J. |title=The Gardener's Guide to Growing Clematis |publisher=Timber Press/David and Charles |year=1998}}</ref> Early-season, large-flowering forms such as 'Nelly Moser' tend towards the natural flowering habit of ''C. patens'' or ''C. lanuginosa'' while later-flowering forms such as ×''jackmanii'' are nearer in habit to ''C. viticella''.