Clematis is agenus of about 380species[2][3] within the buttercup family,Ranunculaceae.[4] Their garden hybrids andcultivars have been popular amonggardeners,[5] beginning withClematis 'Jackmanii', a garden staple since 1862. More cultivars are being produced constantly, mainly of Chinese and Japanese origin.
The genus nameClematis[pronunciation note 1] is fromAncient Greek κληματίς :clēmatís, ("a climbing plant") from κλήμα :klḗma – 'twig, sprout, tendril'.
The genus is composed of mostly vigorous, woody, climbingvines /lianas. The woody stems are quite fragile until several years old.[5] Leaves are opposite and divided intoleaflets and leafstalks that twist and curl around supporting structures to anchor the plant as it climbs.[5] Some species areshrubby, while others, likeC. recta, areherbaceousperennial plants. The cool temperate species aredeciduous, but many of the warmer climate species areevergreen. They grow best in cool, moist, well-drained soil in full sun.[10]
Clematis species are mainly found throughout the temperate regions of the Northern Hemisphere, rarely in the tropics.Clematis leaves are food for thecaterpillars of someLepidopteraspecies, including thewillow beauty (Peribatodes rhomboidaria).
The timing and location of flowers varies; spring-blooming clematis flower on side shoots of the previous year's stems, summer/fall blooming clematis bloom only on the ends of new stems, and twice-flowering clematis do both.[5]
The genusClematis was first published byCarl Linnaeus inSpecies Plantarum in 1753,[11] the first species listed beingClematis viticella. The genus name long pre-dates Linnaeus. It was used inClassical Greek for various climbing plants, and is based on κλήμα (klēma), meaning vine or tendril.[12]
Some morphologically distinctive taxa lacking the combination of characters definingClematis were formerly segregated as the generaArchiclematis (1 species) andNaravelia (several species). DNA sequence studies have found that these two genera are deeply nested inClematis, the morphological characters they were erected on being either reversals or misinterpretations, and that consequently the genera should be reduced to the synonymy ofClematis.Naravelia is a monophyletic group withinClematis.[13][14][15]
Large, dark purple clematis flower with white finger stamens in sunlightPurple clematisClematis armandiiClematis 'Multi Blue'Clematis floridaC. montanaFlowers ofC. vitalbaSeed heads ofC. vitalba growing in ahedge, showing why it is known colloquially as "old man's beard"AchenesFruits ofC. dioica in Guanacaste, Costa RicaC. terniflora seed cluster
One recent classification[which?] recognised 297 species of clematis. Consequently,taxonomists and gardeners subdivide the genus. Several classification systems exist.
Magnus Johnson dividedClematis into 19sections, several with subsections.[25] Christopher Grey-Wilson divided the genus into 9subgenera (Clematis,Cheiropsis, Flammula,Archiclematis,Campanella,Atragene,Tubulosae,Pseudanemone,Viorna), several with sections and subsections within them.[26] 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 subgenusFlammula as defined by Grey-Wilson. These larger-flowered cultivars are often used within garden designs to climb archways,pergolas, or wall-mountedtrellises, or to grow through companion plants. These forms normally have large 12–15 cm diameter upward-facing flowers and are believed to involve crosses ofC. patens,C. lanuginosa, andC. viticella.[27] Early-season, large-flowering forms such as 'Nelly Moser' tend towards the natural flowering habit ofC. patens orC. lanuginosa while later-flowering forms such as ×jackmanii are nearer in habit toC. viticella.
The wildClematis species, such asClematis florida, native to China had also made their way into Japanese gardens by the 17th century.[29] These species were also brought to Europe through Japan.[30]
Japanese garden selections, mostly cultivated inEdo Period using species that are native to Japan or China,[28] were the first exotic clematises to reach European gardens, in the 18th century, long before the Chinese species were identified in their native habitat at the end of the 19th century.[29]
After it arrived in Europe, it acquired several meanings during theVictorian era, famous for its nuancedflower symbolism. It came to symbolize both mental beauty and art as well aspoverty.[31]
The climbing varieties are valued for their ability to scramble up walls, fences, and other structures, and also to grow through other plants, such as shrubs and trees. Some can be trained along the ground to provide cover. Because of their adaptability and masses of spectacular flowers, clematis are among the most popular of all garden plants. Many choice and rare cultivars are to be had from mail order and online catalogues. Specialists regularly put on displays in national flower shows such as theChelsea Flower Show. In theory, it is possible to have a clematis in flower at any time throughout the year. Many varieties provide a second period of interest with a flush of flowers, or decorative seed heads.
They will grow in any good garden soil. The roots usually require a moist, cool substrate, while the herbage can take full sun. Some more delicate cultivars such as 'Nelly Moser' do better in light shade. Many clematis can be grown successfully in containers.[30][32]
Different varieties and cultivars require varied pruning regimes from no pruning to heavy pruning annually.[33] The pruning regime for a cultivated clematis falls into three categories:
Vigorous species and early-flowering hybrids do not require pruning, other than to occasionally remove tangled growth (as inC. armandii,C. montana, andC. tangutica)
Large-flowered hybrids blooming in early summer on the previous season's growth can be pruned lightly in thedormant season for structure
Late-flowering hybrids which bloom on the current season's growth can be pruned back to a pair of buds in the dormant season[34][35]
In the Atragene group are woody deciduous climbers with bell-shaped flowers in spring, produced on the last year's growth. These include 'Markham's Pink', a pale pink breed.[37]
In the early large-flowered group, which flower on the last year's growth, are:
In theClematis integrifolia group (or Integrifolia group) are non- or semi-climbing plants that flower on the current year's growth. These include the violet-pink 'Arabella'.[45]
In the late large-flowered group, which flower on the current year's growth, are:
This follows the classification adopted by V. Matthews in The International Clematis Register and Checklist 2002, except thatC. ispahanica, now considered to have been included in error, has been omitted from the list of parent species in Tangutica Group.[58][59]
Small-flowered Division: Flowers (1.5–)2–12(–18) cm across
Armandii Group: Cultivars belonging to, or derived from, species classified in subsection Meyenianae (Tamura) M. Johnson, mainlyC. armandii.
Atragene Group: Cultivars belonging to, or derived from, species classified in subgenus Atragene (L.) Torrey & A. Gray, such asC. alpina, C. chiisanensis, C. fauriei, C. koreana, C. macropetala, C. ochotensis, C. sibirica, C. turkestanica. The former Alpina Group and Macropetala Group are included here. Historically, the Alpina Group was used for single-flowered cultivars, and double-flowered cultivars were assigned to the Macropetala Group.
Cirrhosa Group: Cultivars belonging to, or derived mainly from,C. cirrhosa.
Flammula Group: Cultivars with at least one parent belonging to, or derived from, species classified in section Flammula DC. (excluding subsection Meyenianae (Tamura)M. Johnson), such asC. angustifolia, C. flammula, C. recta, C. terniflora.
Forsteri Group: Cultivars belonging to, or derived from, species classified in section Novae-zeelandiae M. Johnson (native to Australia and New Zealand) such asC. australis, C. foetida, C. forsteri, C. marata, C. marmoraria, C. paniculata, C. petriei.
Heracleifolia Group: Cultivars with at least one parent belonging to, or derived from, species classified in subgenus Tubulosa (Decne.) Grey-Wilson, such asC. heracleifolia, C. stans, C. tubulosa.
Integrifolia Group: Cultivars belonging to, or derived mainly from,C. integrifolia. Includes the Diversifolia Group (which coveredC. ×diversifolia (C. integrifolia ×C. viticella) and its cultivars).
Montana Group: Cultivars belonging to, or derived from, species classified in section Montanae (Schneider) Grey-Wilson such asC. chrysocoma, C. montana, C. spooneri.
Tangutica Group: Cultivars with at least one parent belonging to, or derived from, species classified in section Meclatis (Spach) Baill., such asC. intricata, C. ladakhiana, C. orientalis, C. serratifolia, C. tangutica, C. tibetana. This Group has also been known as the Orientalis Group.
Texensis Group: Cultivars derived fromC. texensis crossed with representatives from either of the Large-flowered Groups.
Viorna Group: Cultivars with at least one parent belonging to, or derived from, species classified in section Viorna A. Gray, such asC. crispa, C. fusca, C. ianthina, C. pitcheri, C. reticulata, C. texensis, C. viorna. Cultivars assigned to Texensis Group, and cultivars withC. integrifolia in their parentage, are excluded.
Vitalba Group: Cultivars with at least one parent belonging to, or derived from, species classified in section Clematis L., such asC. ligusticifolia, C. potaninii, C. vitalba, C. virginiana.
Viticella Group: Cultivars with at least one parent mainly derived fromC. viticella. Excludes hybrids betweenC. integrifolia andC. viticella: see Integrifolia Group.
Large-flowered Division: Flowers (5–)10–22(–29) cm across, usually flat.
Early Large-flowered Group: Comprises the former Patens Group and Fortunei Group. Cultivars of the Patens Group were derived mainly fromC. patens, either directly or indirectly. They were characterized by producing flowers in spring on the previous year's wood, and often again in summer or early autumn on the current year's growth. The former Fortunei Group (also known as Florida Group, although it had nothing to do withC. florida) comprised cultivars with double or semi-double flowers that were produced on the previous year's growth in spring. Hybridization has made it impossible to keep the original Groups separate: there are a number of cultivars that produce both single and double flowers, or that only produce semi-double or double flowers under certain conditions.
Late Large-flowered Group: Comprises the former Lanuginosa Group and Jackmanii Group. Cultivars of the Lanuginosa Group were derived mainly fromC. lanuginosa, either directly or indirectly. The Jackmanii Group covered cultivars produced from a cross betweenC. viticella (or a derivative therefrom) and a member of the Patens Group. Both Groups produce their flowers on the current year's growth in summer and autumn. It is often impossible to say whether a cultivar belongs to the Lanuginosa Group or to the Jackmanii Group, due to hybridization and/or lack of information on the parentage, so it is not possible to maintain these Groups.
The European species did not enter into theherbalists'pharmacopeia.[60] In theAmerican Old West, the Western white clematis,Clematis ligusticifolia, was calledpepper vine by early travelers and pioneers, who took a tip from Spanish colonials and used seeds and the acrid leaves ofyerba de chivato as apepper substitute.[61] The entire genus containsessential oils and compounds which are extremely irritating to the skin and mucous membranes. Unlike black pepper orCapsicum, however, the compounds in clematis cause internal bleeding of the digestive tract if ingested in large amounts.C. ligusticifolia is essentially toxic. When pruning them, it is a good idea to wear gloves. Despite its toxicity, Native Americans used very small amounts of clematis as an effective treatment formigraine headaches and nervous disorders. It was also used as an effective treatment of skin infections.[62] Clematis is also a constituent ofBach's Rescue Remedy. Leaf extracts from twoEthiopian species (Clematis longicauda steud ex A. Rich. andClematis burgensis Engl.) are used locally to treat ear disorders and eczema. Phytochemical screening of the extracts from both of these species showed antibacterial and antifungal activity.[63] The extracts of these plants also possess wound healing and anti-inflammatory activities which could also be attributed to the phytoconstituents.[64]
Clematis has been listed as one of the 38 plants used to prepareBach flower remedies,[65] a kind ofalternative medicine promoted for its effect on health. However, according toCancer Research UK, "there is no scientific evidence to prove that flower remedies can control, cure or prevent any type of disease, including cancer".[66]
Clematis species are susceptible to several pests and diseases. Clematis wilt, a stem rot caused by the fungusPhoma clematidina, causes dramatic wilting and death of whole branches, although many species are resistant to it.[67] The species of this genus are alsoalternate hosts ofPuccinia recondita f.sp.tritici.[68]: 3 C. mandshurica specifically is known to provideinoculum transferrable towheat in the former easternSoviet territories, and several of this genus are hosts for several otherP. recondita strains[68]: 8 and otherPuccinia.[68]: 25 Other pests and diseases includepowdery mildew,viruses,slugs andsnails, scale insects,aphids,earwigs, and green flower disease, which is usually caused by infection with aphytoplasma, a type of bacterium.[69]
^ab"Genus:Clematis L."Germplasm Resources Information Network. United States Department of Agriculture. 2000-12-20. Archived fromthe original on 2009-06-17. Retrieved2011-02-02.
^Of the native EuropeanC. vitalba Alice Coats observes "The leaves are acrid and poisonous, and not even the early herbalists attempted to use the plant in internal medicine", but she notes thatJohn Gerard calledClematis flammula biting clematis or purging periwinkle. (Coats 1992).
