You are here
Magnoliopsida
Hedera helix L.
EOL Text
Ivy belongs to the Araliaceae, or ginsengs, a mainly tropical family of trees, shrubs, woody lianes (vines) and a few herbs.The ivy genus, Hedera, has recently been expanded to contain 15 species, but not all botanists agree. The similarities between the species are reflected in the fact that all have, at some time or another, been viewed as variants of Hedera helix.
Description
Ivy is a woody, evergreen climber. In suitable conditions it can reach 30m high with stems up to 25cm in diameter, but it can also creep along the ground.The stems are clothed in hair-like roots which are adhesive, enabling the plant to cling to hard surfaces.The leaves are:
- hairless
- dark green above
- pale green beneath
- glossy
- rather leathery
Leaves on creeping or climbing stems have blades with 3 to 5 triangular lobes, whereas those of flowering branches have oval or rhombic blades, without lobes.The flowers are borne in umbrella-like clusters, with all the stalks arising from a single point. They have 5 broad greenish yellow petals 3–4mm long and are followed by globose, dull black fruits which ripen in the following spring.When rubbed, the berries have an aromatic scent but a bitter and nauseous taste.There are hundreds of cultivars of ivy, mainly differing in their leaves which are very variable in size, colour, number and depth of lobes. The leaves are often variegated green and any one of a wide range of colours but particularly white, cream, yellow or gold. They are popular as garden ornamentals and as house plants.Several plants can be confused with ivy, mainly because of their names. Two are found in North America and are completely unrelated to ivy. They are:
- Boston ivy (Parthenocissus tricuspidata) - a climber with lobed leaves that is a member of the grape family. It is deciduous and clings by means of tendrils with small suckers.
- Poison ivy (Toxicodendron radicans) - this grows as a climbing vine or a small shrub with leaves divided into three leaflets. The sap contains a compound which causes an irritant rash when any part of the plant is touched.
Another species that can cause confusion is ground ivy (Glechoma hederacea) - this is a European herb related to the mints which was used to brew ale.
License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
Rights holder/Author | Bob Press and Jacek, Natural History Museum |
Source | No source database. |
Ivy is one of a small number of plants that exhibit different juvenile and adult forms.Young growth consists of creeping or climbing stems bearing numerous fine, aerial roots and (usually) lobed leaves - this is what most people think of as ‘typical’ ivy. It’s the vigorous growth stage, when the plant spreads rapidly.When the plant reaches maturity it produces rootless, self-supporting stems with unlobed leaves. The adult growth bears the flowers and fruits but these are only produced in full sun. Very old ivies may look more like shrubs than climbers.Ivy flowers very late in the year, from September to December. The flowers are pollinated by wasps and moths, providing a useful food source for these insects.
License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
Rights holder/Author | Bob Press and Jacek, Natural History Museum |
Source | No source database. |
More info for the terms: fire suppression, fuel, invasive species, prescribed fire, restoration, shrubs
Preventing postfire establishment and spread: English ivy may establish after fire by seed on sites where it did not previously occur (see Plant response to fire). Preventing its establishment in burned areas is the most effective and least costly management method of control. This may be accomplished through early detection and eradication, careful monitoring and follow-up, and limiting dispersal of its seed into burned areas. General recommendations for preventing postfire establishment and spread of invasive plants include:
- Incorporate cost of weed prevention and management into fire rehabilitation plans
- Acquire restoration funding
- Include weed prevention education in fire training
- Minimize soil disturbance and vegetation removal during fire suppression and rehabilitation activities
- Minimize the use of retardants that may alter soil nutrient availability, such as those containing nitrogen and phosphorus
- Avoid areas dominated by high priority invasive plants when locating firelines, monitoring camps, staging areas, and helibases
- Clean equipment and vehicles prior to entering burned areas
- Regulate or prevent human and livestock entry into burned areas until desirable site vegetation has recovered sufficiently to resist invasion by undesirable vegetation
- Monitor burned areas and areas of significant disturbance or traffic from management activity
- Detect weeds early and eradicate before vegetative spread and/or seed dispersal
- Eradicate small patches and contain or control large infestations within or adjacent to the burned area
- Reestablish vegetation on bare ground as soon as possible
- Avoid use of fertilizers in postfire rehabilitation and restoration
- Use only certified weed-free seed mixes when revegetation is necessary
For more detailed information on these topics, see the following publications: [6,15,47,178].
Use of prescribed fire as a control agent: As of this writing (2010), no information was available on the use of prescribed fire to control English ivy. Several invasive species publications indicated that repeat burning with a blowtorch at regular intervals has had some success in controlling English ivy; however, no examples using this method were described [25,125,190]. Although blowtorching may not directly kill English ivy, it may deplete its energy reserves by causing it to continually sprout, which may eventually kill it [125]. Reichard [125] cautioned that this approach requires considerable care. This approach also seems infeasible for large populations of English ivy.
Altered fuel characteristics: Researchers in the northeastern United States speculate that English ivy may alter fuel characteristics by acting as ladder fuel (see Fuels) or by killing the trees and shrubs on which it climbs [29].
Ivy is native to Europe and western Asia, occurring in woods, hedges and rocky areas. It grows up any suitable surface or creeps along the ground.It thrives on all but the driest, most water-logged or very acid soils and is very tolerant of shade.It has been introduced to many countries, notably the USA and Australia.
License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
Rights holder/Author | Bob Press and Jacek, Natural History Museum |
Source | No source database. |
English ivy is an aggressive invader that threatens all vegetation levels of forested and open areas, growing along the ground as well as into the forest canopy. Vines climbing up tree trunks spread out and envelop branches and twigs, blocking sunlight from reaching the host tree’s foliage, thereby impeding photosynthesis. An infested tree will exhibit decline for several to many years before it dies. The added weight of vines also makes trees susceptible to blowing over during storms. English ivy has been confirmed as a reservoir for bacterial leaf scorch (Xylella fastidiosa), a harmful plant pathogen that affects a wide variety of native and ornamental trees such as elms, oaks and maples.
License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
Rights holder/Author | U.S. National Park Service |
Source | http://www.nps.gov/plants/alien/pubs/midatlantic/hehe.htm |
Canada
Origin: Exotic
Regularity: Regularly occurring
Currently: Unknown/Undetermined
Confidence: Confident
United States
Origin: Exotic
Regularity: Regularly occurring
Currently: Unknown/Undetermined
Confidence: Confident
License | http://creativecommons.org/licenses/by-nc/3.0/ |
Rights holder/Author | NatureServe |
Source | http://explorer.natureserve.org/servlet/NatureServe?searchName=Hedera+helix |
More info for the terms: fire frequency, fire intensity, fire regime, frequency, fuel, severity
In its nonnative range in North America, English ivy occurs in plant communities with variable FIRE REGIMES, but at the time of this writing (2010), no information was available on how it responds to or influences FIRE REGIMES in these communities. Land managers in the Pacific Northwest speculated that English ivy may influence riparian FIRE REGIMES; however, the magnitude and direction of its effects on fuel characteristics and FIRE REGIMES is unknown. In moist forests where English ivy occurs, extreme fire weather may be a more important driving force of fire intensity and severity than fuel characteristics [1]; therefore, even if English ivy causes marked changes in fuel characteristics, it may have little or no influence on local FIRE REGIMES [4].
Studies from Europe indicate that English ivy occurs in communities with variable fire frequency. On the Iberian Peninsula in Spain, English ivy is associated with plant communities occurring in warm, dry Mediterranean climates that are subject to high fire frequency and montane vegetation in subhumid climates where fires are rare [181]. In southern Switzerland, English ivy occurred in forest types that had mean fire-return intervals ranging from 7 to more than 100 years, but its frequency was generally lower in areas with greater fire frequency (see Plant response to fire).
See the Fire Regime Table for further information on FIRE REGIMES of vegetation communities in which English ivy may occur.
There has been considerable discussion and controversy, about ivy’s effect on trees, buildings and other structures:
- clinging roots are thought to penetrate walls causing physical damage to the structure and allowing ingress of water
- some say it literally strangles trees as the ivy stems become thicker with age
- heavy growth of ivy on buildings and trees is believed to increase the risk of windthrow - damage caused by the resistance of the foliage to high winds
However, these views have been challenged:
- well-maintained brickwork is now thought to be relatively unaffected by ivy and even to benefit from the protection the plant covering offers
- evidence for damage to trees is also disputed
- good growth of ivy on buildings certainly offers shelter for other wildlife
License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
Rights holder/Author | Bob Press and Jacek, Natural History Museum |
Source | No source database. |
Hedera helix (common ivy, English ivy, European ivy, or just ivy) is a species of flowering plant in the family Araliaceae, native to most of Europe and western Asia. A rampant, clinging evergreen vine, it is a familiar sight in gardens, waste spaces, on house walls, tree trunks and in wild areas across its native habitat. It is labeled as an invasive species in a number of areas where it has been introduced.
Contents
Etymology[edit]
Hedera is the generic term for ivy. The specific epithet helix derives from Ancient Greek "twist, turn" (see: Helix).[1]
Synonyms[edit]
Synonyms include Hedera acuta, Hedera arborea ("tree ivy"),[2]Hedera baccifera, Hedera grandifolia,[3] English Ivy, Bindwood, and Lovestone.
Description[edit]
Hedera helix is an evergreen climbing plant, growing to 20–30 m (66–98 ft) high where suitable surfaces (trees, cliffs, walls) are available, and also growing as groundcover where there are no vertical surfaces. It climbs by means of aerial rootlets with matted pads which cling strongly to the substrate.
The leaves are alternate, 50–100 mm long, with a 15–20 mm petiole; they are of two types, with palmately five-lobed juvenile leaves on creeping and climbing stems, and unlobed cordate adult leaves on fertile flowering stems exposed to full sun, usually high in the crowns of trees or the top of rock faces.
The flowers are produced from late summer until late autumn, individually small, in 3–5 cm diameter umbels, greenish-yellow, and very rich in nectar, an important late autumn food source for bees and other insects.
The fruit are purple-black to orange-yellow berries 6–8 mm diameter, ripening in late winter,[4] and are an important food for many birds, though somewhat poisonous to humans.
There are one to five seeds in each berry, which are dispersed by birds eating the berries.[5][6][7]
There are three subspecies:[5][8]
- Hedera helix subsp. helix.
Central, northern and western Europe. Plants without rhizomes. Purple-black ripe fruit. - Hedera helix subsp. poetarum Nyman (syn. Hedera chrysocarpa Walsh).
Southeast Europe and southwest Asia (Italy, Balkans, Turkey). Plants without rhizomes. Orange-yellow ripe fruit. - Hedera helix subsp. rhizomatifera
McAllister. Southeast Spain. Plants rhizomatiferous. Purple-black ripe fruit.
The closely related species Hedera canariensis and Hedera hibernica are also often treated as subspecies of H. helix,[7][9] though they differ in chromosome number so do not hybridise readily.[6]H. helix can be best distinguished by the shape and colour of its leaf trichomes, usually smaller and slightly more deeply lobed leaves and somewhat less vigorous growth, though identification is often not easy.[7][10]
Range[edit]
It ranges from Ireland northeast to southern Scandinavia, south to Portugal, and east to Ukraine and Iran and northern Turkey.
The northern and eastern limits are at about the −2°C winter isotherm, while to the west and southwest, it is replaced by other species of ivy.[5][6][7][8][9][11]
Cultivation and uses[edit]
It is widely cultivated as an ornamental plant. Within its native range, the species is greatly valued for attracting wildlife. The flowers are visited by over 70 species of nectar-feeding insects, and the berries eaten by at least 16 species of birds. The foliage provides dense evergreen shelter, and is also browsed by deer.[5][12]
The species can become a nuisance in gardens, rapidly colonising hedges, trees and borders if not kept in check. It can even invade neglected lawns. Over 30 cultivars have been selected for such traits as yellow, white, variegated (e.g. 'Glacier'), and/or deeply lobed leaves (e.g. 'Sagittifolia'), purple stems, and slow, dwarfed growth.[13]
The following cultivars have gained the Royal Horticultural Society's Award of Garden Merit:-
Ethnomedical uses[edit]
In the past, the leaves and berries were taken orally as an expectorant to treat cough and bronchitis.[24] In 1597, the British herbalist John Gerard recommended water infused with ivy leaves as a wash for sore or watering eyes.[25] The leaves can cause severe contact dermatitis in some people.[26][27] People who have this allergy (strictly a Type IV hypersensitivity) are also likely to react to carrots and other members of the Apiaceae as they contain the same allergen, falcarinol.
Invasive species[edit]
Like other exotic species, Ivy has predominantly been spread to areas by human action. H. helix is labeled as an invasive species in many parts of the United States, and its sale or import is banned in the state of Oregon.[28]
Laurus nobilis and Ilex aquifolium are widespread relicts of the laurisilva forests that originally covered much of the Mediterranean Basin when the climate of the region was more humid during the tertiary era. Having disappeared during the glaciation, Ivy is believed to have been spread back across the continent by birds once the continent warmed up again.[29] With a great capacity for adaptation, Ivy will grow wherever development conditions and habitat similar to that of its European origins exist, occurring as opportunistic species across a wide distribution with close vicariant relatives and few species, indicating recent speciation.
Australia[edit]
It is considered a noxious weed across southern, particularly south-eastern, Australia and local councils provide free information and limited services for removal. In some councils it is illegal to sell the plant. It is a weed in the Australian state of Victoria.[30]
New Zealand[edit]
H. helix has been listed as an "environmental weed" by the Department of Conservation since 1990.[31]
United States[edit]
In the United States, H. helix is considered weedy or invasive in a number of regions and is on the official noxious weed lists in Oregon and Washington.[32] Like other invasive vines such as kudzu, H. helix can grow to choke out other plants and create "ivy deserts". State- and county-sponsored efforts are encouraging the destruction of ivy in forests of the Pacific Northwest and the Southern United States.[33][34] Its sale or import is banned in Oregon.[35] Ivy can easily escape from cultivated gardens and invade nearby parks, forests and other natural areas.
Control and Eradication[edit]
English Ivy should not be planted or encouraged in areas where it is invasive. Where it is established, it is very difficult to control or eradicate. In the absence of active and ongoing measures to control its growth, it will tend to crowd out all other plants, including shrubs and trees.
Damage to trees[edit]
Ivy can climb into the canopy of young or small trees in such density that the trees fall over from the weight,[34] a problem which does not normally occur in its native range.[5] However, this is not the primary mechanism by which ivy kills large trees. Ivy kills mature and well-established trees primarily by girdling, and by water and nutrient competition. This can be seen in the inexorable death of mature trees that are not bent by the weight of the ivy on their trunks. Ivy grows in a dense mat on the trunk and around the base of trees, creating buildup of organic matter and habitat for bark-damaging organisms. Ground-running stems of ivy can wrap tightly around the base of the tree, constricting the tree as it grows and cutting into the phloem. For this reason, it is especially important to remove ivy not only from the trunk of trees, but also from the ground at their base, creating "survival rings". In its mature form, dense ivy can destroy habitat for native wildlife and creates large sections of solid ivy where no other plants can develop.[34]
Damage to buildings[edit]
Ivy covering the walls of an old building is a familiar and often attractive sight. It may have insulating benefits, but can be problematic if not managed correctly. Ivy, and especially European ivy (H. helix) grows extremely rapidly and clings by means of fibrous roots which develop along the entire length of the stems. These are difficult to remove, leaving an unsightly "footprint" on walls, and possibly resulting in expensive resurfacing work. Additionally, ivy can quickly invade gutters and roofspaces, lifting tiles and causing blockages. It also harbours mice and other unwelcome creatures. The plants have to be cut off at the base, and the stumps dug out or killed to prevent regrowth.[36]
References[edit]
- ^ Harrison, Lorraine (2012). RHS Latin for gardeners. United Kingdom: Mitchell Beazley. p. 224. ISBN 978-1-84533-731-5.
- ^ Bean, W. J. (1978) Trees and Shrubs Hardy in the British Isles Volume 2.
- ^ International Plant Names Index
- ^ RHS A-Z encyclopedia of garden plants. United Kingdom: Dorling Kindersley. 2008. p. 1136. ISBN 1-4053-3296-4.
- ^ a b c d e Metcalfe, D. J. (2005). Biological Flora of the British Isles no. 268 Hedera helix L. Journal of Ecology 93: 632–648.
- ^ a b c McAllister, H. (1982). New work on ivies. Int. Dendrol. Soc. Yearbook 1981: 106-109.
- ^ a b c d Flora of NW Europe
- ^ a b Ackerfield, J. & Wen, J. (2002). A morphometric analysis of Hedera L. (the ivy genus, Araliaceae) and its taxonomic implications. Adansonia sér. 3, 24 (2): 197-212.
- ^ a b Flora Europaea: Hedera helix
- ^ The Holly and the Ivy. Shropshire Botanical Society Newsletter Autumn 2000: page 14
- ^ Stace, C. A. & Thompson, H. (1997). New Flora of the British Isles. Cambridge University Press ISBN 0-521-58935-5
- ^ Plant for Wildlife: Common Ivy (Hedera helix)
- ^ NCCPG Plant Heritage: The common ivy
- ^ "RHS Plant Selector - Hedera helix 'Angularis aurea'". Retrieved 21 June 2013.
- ^ "RHS Plant Selector - Hedera helix 'Caecilia'". Retrieved 21 June 2013.
- ^ "RHS Plant Selector - Hedera helix 'Congesta'". Retrieved 21 June 2013.
- ^ "RHS Plant Selector - Hedera helix 'Duckfoot'". Retrieved 21 June 2013.
- ^ "RHS Plant Selector - Hedera helix 'Glacier'". Retrieved 21 June 2013.
- ^ "RHS Plant Selector - Hedera helix 'Goldchild'". Retrieved 21 June 2013.
- ^ "RHS Plant Selector - Hedera helix 'Manda's Crested'". Retrieved 21 June 2013.
- ^ "RHS Plant Selector - Hedera helix 'Midas Touch'". Retrieved 21 June 2013.
- ^ "RHS Plant Selector - Hedera helix 'Parsley Crested'". Retrieved 21 June 2013.
- ^ "RHS Plant Selector - Hedera helix 'Spetchley'". Retrieved 21 June 2013.
- ^ Bown. D. (1995). Encyclopaedia of Herbs and their Uses. Dorling Kindersley, London. ISBN 0-7513-0203-1
- ^ Gerard, John; Woodward, Marcus (ed.) (1985). Gerard's Herbal: The History of Plants. New York: Crescent Books. ISBN 0-517-46470-5
- ^ Jøhnke, H & Bjarnason, B. (1994). Contact dermatitis allergy to common ivy (Hedera helix L.). Ugeskr. Laeger 156 (25): 3778–3779. Abstract
- ^ Boyle, J. & Harman, R. M. H. (2006). Contact dermatitis to Hedera helix (Common Ivy). Contact Dermatitis 12 (2): 111–112. doi:10.1111/j.1600-0536.1985.tb01067.x
- ^ Oregon bans sale of English ivy, butterfly bushes
- ^ http://www.invasive.org/browse/subinfo.cfm?sub=3027
- ^ "English Ivy (Hedera helix)". The State of Victoria. Retrieved 17 September 2010.
- ^ Howell, Clayson (May 2008). Consolidated list of environmental weeds in New Zealand. DRDS292. Wellington: Department of Conservation. ISBN 978-0-478-14413-0. Retrieved 2009-05-06.
- ^ USDA Plants Profile: Hedera helix
- ^ Ivy chasers in a league of their own
- ^ a b c Controlling English Ivy Arlington County, Virginia Department of Parks, Recreation and Community Resources.
- ^ Controlling English Ivy. Northwest Coalition for Alternatives to Pesticides.
- ^ "Ivy on buildings". Royal Horticultural Society. Retrieved 21 June 2013.
License | http://creativecommons.org/licenses/by-sa/3.0/ |
Rights holder/Author | Wikipedia |
Source | http://en.wikipedia.org/w/index.php?title=Hedera_helix&oldid=654096082 |
More info for the term: invasive species
Nonnative range: English ivy is nonnative to North America. In the eastern United States, it occurs from Massachusetts south throughout the mid-Atlantic and southeastern states to Florida and across the south-central states as far east as Texas. It occurs in some of the Great Lakes states including Michigan, Indiana, and Illinois [108,179], and in Ontario, Canada [108]. One invasive plant publication indicated it also occurred in Wisconsin [25]. In the West, English ivy occurs in all Pacific Coast states and British Columbia, in addition to Idaho, Utah, and Arizona [108,179]. It also occurs in Hawaii [186].
Based on regional floras [30,46,60,92,103,104,122,186,196], invasive plant publications [25,125,193], and websites [17,45,74,96,101,106,113,149,163,176,177], English ivy is most invasive in the Pacific Northwest. Based on a regional invasive species map, English ivy is not widespread in the Southeast [100], but it may be locally abundant in some mid-Atlantic states including Virginia [115,117], West Virginia, and in some southern states including North Carolina, South Carolina, Alabama, and Arkansas [100]. Several sources indicate that English ivy is not as problematic in the Northeast as in the Pacific Northwest, mid-Atlantic, and Southeast. A review of floristic surveys from the eastern United States found that English ivy occurred in temperate forests in this area but was not common [88]. Local floras indicate that English ivy occasionally escapes cultivation in the Northeast [46,92], and English ivy is not listed on a Northeastern invasive species website [96]. It may, however, be locally abundant in parts of Washington, DC [164,170]. NatureServe provides a map of English ivy's North American distribution.
Brought to North America by colonial settlers [99,125,146], English ivy was first documented in North America in Virginia around 1800 [191]. Since then English ivy has been widely cultivated as an ornamental [90,104,138,184,192], although its cultivation in Hawaii did not begin until the early 1900 [186]. In many places where it is planted, English ivy escapes cultivation to varying degrees [46,92,103,104,122,195] and invades and persists in wildlands [30,60,138,186,190,195].
English Ivy has been introduced to South Africa, India, Australia, New Zealand, Brazil, and Mexico [97,190].
Native range: English ivy is native to Eurasia [46,52,103,104,186,192,196], occurring from the Caucasus Mountains [184,186] to Norway [52,145] and south to Iran [97] and northern Africa [97,184]. It tends to be less abundant north of the Alps [145].