Hedera
Hedera | |
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Hedera algeriensis in Lincoln Park Conservatory, Chicago | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Asterids |
Order: | Apiales |
Family: | Araliaceae |
Subfamily: | Aralioideae |
Genus: | Hedera L. |
Species | |
See text | |
Synonyms[1] | |
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Hedera, commonly called ivy (plural ivies), is a genus of 12–15 species of
. Several species are cultivated as climbing ornamentals, and the name ivy especially denotes common ivy (Hedera helix), known in North America as "English ivy", which is frequently planted to clothe brick walls.Description
On level ground ivies remain creeping, not exceeding 5–20 cm height, but on surfaces suitable for climbing, including
The species differ in detail of the leaf shape and size (particularly of the juvenile leaves) and in the structure of the leaf trichomes, and also in the size and, to a lesser extent, the colour of the flowers and fruit. The chromosome number also differs between species. The basic diploid number is 48, while some are tetraploid with 96, and others hexaploid with 144 and octaploid with 192 chromosomes.[2]
Ecology
Ivies are natives of Eurasia and North Africa but have been introduced to North America and Australia. They invade disturbed forest areas in North America.[3] Ivy seeds are spread by birds.[3]
Ivies are of major ecological importance for their nectar and fruit production, both produced at times of the year when few other nectar or fruit sources are available.
A very wide range of invertebrates shelter and overwinter in the dense woody tangle of ivy.[6] Birds and small mammals also nest in ivy.[7] It serves to increase the surface area and complexity of woodland environments.
Taxonomy
The following species are widely accepted; they are divided into two main groups, depending on whether they have scale-like or stellate trichomes on the undersides of the leaves:[2][8][9]
- Trichomes scale-like
- Hedera algeriensis Hibberd – Algerian ivy. Algeria, Tunisia (Mediterranean coast).
- Hedera canariensis Willd. – Canaries ivy. Canary Islands.
- Hedera colchica (K.Koch) K.Koch – Persian ivy. Alborz, Caucasus, Turkey.
- Hedera cypria McAllister – Cyprus ivy (syn. H. pastuchovii subsp. cypria (McAll.) Hand). Cyprus (Troodos Mts.)
- Hedera iberica (McAllister) Ackerfield & J.Wen – Iberian ivy. SW Iberian coasts.
- Hedera maderensis – Madeiran ivy. Madeira.
- Hedera maroccana McAllister – Moroccan ivy. Morocco.
- Hedera nepalensis K.Koch – Himalayan ivy (syn. H. sinensis (Tobl.) Hand.-Mazz.). Himalaya, SW China.
- Hedera pastuchovii G.Woronow – Pastuchov's ivy. Caucasus, Alborz.
- Hedera rhombea (Miq.) Siebold ex Bean – Japanese ivy. Japan, Korea, Taiwan.
- Trichomes stellate
- Hedera azorica Carrière – Azores ivy. Azores.
- Hedera helix L. – Common ivy (syn. H. caucasigena Pojark., H. taurica (Hibberd) Carrière). Europe, and widely introduced elsewhere.
- Hedera hibernica (G.Kirchn.) Bean – Atlantic ivy (syn. H. helix subsp. hibernica (G.Kirchn.) D.C.McClint.). Atlantic western Europe.
The species of ivy are largely allopatric and closely related, and many have on occasion been treated as varieties or subspecies of H. helix, the first species described. Several additional species have been described in the southern parts of the former Soviet Union, but are not regarded as distinct by most botanists.
Hybrids have been recorded between several Hedera species, including Atlantic ivy (H hibernica) with common ivy (H helix).
Uses and cultivation
Ivies are very popular in cultivation within their native range and compatible climates elsewhere, for their evergreen foliage, attracting wildlife, and for adaptable design uses in narrow planting spaces and on tall or wide walls for aesthetic addition, or to hide unsightly walls, fences and tree stumps. Numerous cultivars with variegated foliage and/or unusual leaf shapes have been selected for horticultural use.[11]
The American Ivy Society is the International Cultivar Registration Authority for Hedera, and recognises over 400 registered cultivars.[13]
Problems and dangers
On trees
Much discussion has involved whether or not ivy climbing trees will harm trees. In Europe, the harm is generally minor although there can be competition for soil nutrients, light, and water, and senescent trees supporting heavy ivy growth can be liable to windthrow damage.[4] The UK's Woodland Trust says "Ivy has long been accused of strangling trees, but it doesn’t harm the tree at all, and even supports at least 50 species of wildlife."[6] Harm and problems are more significant in North America, where ivy is without the natural pests and diseases that control its vigour in its native continents; the photosynthesis or structural strength of a tree can be overwhelmed by aggressive ivy growth leading to death directly or by opportunistic disease and insect attacks.[14]
Invasive exotic
Several ivy species have become a serious invasive species (invasive exotic) in natural native plant habitats, especially riparian and woodland types, and also a horticultural weed in gardens of the western and southern regions of North America with milder winters. Ivies create a dense, vigorously smothering, shade-tolerant evergreen groundcover that can spread through assertive underground rhizomes and above-ground runners quickly over large natural plant community areas and outcompete the native vegetation. The use of ivies as ornamental plants in horticulture in California and other states is now discouraged or banned in certain jurisdictions.[15] Similar problems exist in Australia. For example, in both countries the North African drought-tolerant H. canariensis and H. algeriensis and European H. helix were originally cultivated in garden, park, and highway landscaping, but they have become aggressively invasive in coastal forests and riparian ecosystems, now necessitating costly eradication programs.[16]
Toxicity
The berries are moderately toxic to humans. Ivy foliage contains triterpenoid saponins and falcarinol. Falcarinol is capable of inducing contact dermatitis. It has also been shown to kill breast cancer cells.[17]
Stinging insects
The flowers of ivy are pollinated by
Etymology and other names
The name ivy derives from
The name ivy has also been used as a common name for a number of other unrelated plants, including Boston ivy (Japanese Creeper Parthenocissus tricuspidata, in the family Vitaceae), Cape-ivy (used interchangeably for Senecio angulatus and Delairea odorata, Asteraceae), poison-ivy (Toxicodendron radicans, Anacardiaceae), Swedish ivy (Whorled Plectranthus Plectranthus verticillatus, Lamiaceae) and ground ivy (Glechoma hederacea, also Lamiaceae), and Kenilworth ivy (Cymbalaria muralis, Plantaginaceae).
Cultural symbolism
Like many other evergreen plants, which impressed European cultures by persisting through the winter, ivy has traditionally been imbued with a spiritual significance. It was brought into homes to drive out evil spirits.[6]
In
Ivy bushes or ivy-wrapped poles have traditionally been used to advertise taverns in the United Kingdom, and many pubs are still called The Ivy.[19]
The clinging nature of ivy makes it a symbol of love and friendship, there was once a tradition of priests giving ivy to newlyweds,[6] and as it clings to dead trees and remains green, it was also viewed as a symbol of the eternal life of the soul after the death of the body in medieval Christian symbolism.[20]
The traditional British
Ivy-covered ruins were a staple of the
The image of ivy-covered historic buildings gave the name Ivy League to a group of old and prestigious American universities. [21]
Ivy features extensively in the 2010 movie Arrietty and the poster for the film.
Gallery
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Hedera helix on trees near Srbsko, Czech Republic
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Hedera colchica leaves and flowers
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Hedera hibernica with berries
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Hedera helix leaves, Bremerhaven
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Hedera helix flowers
See also
References
- ^ "World Checklist of Selected Plant Families". Retrieved June 11, 2014.
- ^ a b c Ackerfield, J, & Wen, J. (2002). A morphometric analysis of Hedera L. (the ivy genus, Araliaceae) and its taxonomic implications. Adansonia sér. 3, 24: 197-212. Full text. Archived 2011-08-08 at the Wayback Machine
- ^ S2CID 86767633.
- ^ a b c Mitchell, A. F. (1975). "Three Forest Climbers: Ivy, Old Man's Beard and Honeysuckle". Forest Record. 102.
- ^ Hymettus — BWARS Information Sheet: Ivy Bee (Colletes hederae) Archived 2011-04-28 at the Wayback Machine
- ^ a b c d e "Ivy (Hedera helix)". Woodland Trust. Retrieved 23 December 2019.
- ^ English Heritage - Ivy on Walls Seminar Report, 19 May 2010 www.geog.ox.ac.uk, accessed 11 November 2020
- ^ McAllister, H. (1982). New work on ivies Int. Dendrol. Soc. Yearbook 1981: 106–109.
- ^ Germplasm Resources Information Network Species Records of Hedera Archived 2015-09-24 at the Wayback Machine
- ^ R H Marshall, H A McAllister & J D Armitage (2017), A summary of hybrids detected in the genus Hedera (Araliaceae) with the provision of three new names, New Journal of Botany, 7:1, 2-8 [1]
- ^ ISBN 0-333-47494-5.
- ^ Metcalfe, D. J. (2005). Biological Flora of the British Isles no. 268 Hedera helix L. Journal of Ecology 93: 632–648.
- ^ "Ivies". The American Ivy Society. Retrieved 12 October 2023.
- ^ "Hedera helix". www.fs.fed.us. Retrieved 2021-01-21.
- ^ "Criteria for Categorizing Invasive Non-native Plants that Threaten Wildlands" (PDF). Cal-IPC. 2003-02-28. Archived from the original (PDF) on 2010-06-12. Retrieved 2010-04-01.
- ^ "California Invasive Plant Council Interactive Database". Cal-IPC. Retrieved 2014-05-27.
- PMID 15740080.
- ^ Werner, W. (2009). The Terminology of Medicinal Plants in English and German. Linguistic and didactic aspects (PDF).
- ^ the-history-of-pub-names Ordnance Survey guides getoutside.ordnancesurvey.co.uk, accessed 11 November 2020
- ^ Dictionary of Symbolism: Cultural icons and the meaning behind them, by Hans Beidermann, translated by James Hulbert 1992 P.187
- ^ Harper, Douglas. "ivy". Etymonline. Retrieved 24 December 2020.
External links
- Kew plant profiles: Hedera helix (common ivy)
- Hutchison, Peter (14 May 2010). "Ivy is good for walls, finds Oxford University study". The Telegraph. Telegraph. Archived from the original on 20 May 2010. Retrieved 13 March 2014.
- Walkowiak, Radoslaw (2020). "Hedera helix ssp. helix, leaves of a wild specimen". ResearchGate. CTC Digital Plant Collection.