Hedera helix, simply ivy, or common ivy, English ivy, European ivy, or King's choice ivy, is a species of flowering plant in the family Araliaceae. It is native to most of Europe and parts of western Asia. Ivy is a clinging evergreen vine that grows on tree trunks, walls, and fences in gardens, waste spaces, and wild habitats. Ivy is common as an ornamental plant, but escaped plants become naturalised outside its native range. Ivy has considerable cultural significance and symbolism.
Synonyms include Hedera acuta, Hedera arborea ('tree ivy'),Bean, W. J. (1978) Trees and Shrubs Hardy in the British Isles Volume 2. Hedera baccifera, and Hedera grandifolia.International Plant Names Index Other common names are bindwood and lovestone.
Description Hedera helix is an evergreen climbing plant, growing to high where suitable surfaces (trees, cliffs, walls) are available, and also growing as groundcover where no vertical surfaces occur. It climbs by means of aerial rootlets with matted pads which cling strongly to the substrate. The ability to climb on surfaces varies with the plant's variety and other factors: H. helix prefers non-reflective, darker and rough surfaces with near-neutral pH. It generally thrives in a wide range of soil pH with 6.5 being ideal, prefers moist, shady locations and avoids exposure to direct sunlight, the latter promoting drying out in winter.
The leaves are alternate, long, with a 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 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 in diameter, ripening in late winter, and are an important food source for many birds.
One to five seeds are in each berry, which are dispersed after being eaten by birds.
Subspecies The three subspecies are:
H. h. helix − central, northern and western Europe, plants without rhizomes, purple-black ripe fruit, H. h. poetarum Nyman (syn. Hedera chrysocarpa Walsh) (Italian ivy, poet's ivy) − southeast Europe and southwest Asia (Italy, Balkans, Turkey), plants without rhizomes, orange-yellow ripe fruit, H. h. rhizomatifera McAllister − southeast Spain, plants rhizomatous, purple-black ripe fruit.
The closely related species Hedera canariensis and Hedera hibernica are also often treated as subspecies of H. helix, though they differ in chromosome number and so do not hybridise readily. 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.The Holly and the Ivy. Shropshire Botanical Society Newsletter Autumn 2000: page 14
Etymology The genus name is the Classical Latin word for 'ivy', which is cognate with Greek () 'to get, grasp', both deriving ultimately from Proto-Indo-European 'to seize, grasp, take'. Lionel Horton-Smith,ΚΙΣΣΟΣ and Hedera, The American Journal of Philology, 16,1 1895 pp.38-45 p.38 The specific epithet helix was borrowed into Latin from Ancient Greek (), 'helix', 'spiral'.. The binomial in its entirety thus has the meaning "the clinging plant that coils in spirals (helices)".
Distribution and habitat
The range of Hedera helix is from Ireland northeast to southern Scandinavia, south to Portugal, and east to Ukraine, Iran and northern Turkey. In Britain, it is very common and widespread, but absent from the Isle of Man and Channel Islands.Poland J, Clement EJ. 2020. The Vegetative Key to the British Flora. John Poland, Southampton, Second Edition.
The northern and eastern limits are at about the winter isotherm, while to the west and southwest, it is replaced by other species of ivy.Flora of NW Europe ADANSONIA, sér. 3Flora Europaea: Hedera helixStace, C. A. & Thompson, H. (1997). New Flora of the British Isles. Cambridge University Press Hedera helix itself is much more winter-hardy and survives temperatures of (USDA Zone 6a) and above.
Invasive species
Like other exotic species, ivy has predominantly been spread by human action. H. helix is labeled as an invasive species in parts of the world.
Australia The Centre for Invasive Species Solutions lists Hedera helix as a weed across southern, especially south-eastern Australia, and local councils provide advice on how to remove it and limited services for removal. It is officially scheduled as a weed in Western Australia and the Australian Capital Territory. Hedera helix is the only species of ivy bearing the legal status of 'declared weed' in Australia; however, it may be the case that much of what is identified as invasive "English Ivy" in Australia is in reality Hedera hibernica.
Canada Although common as a winter holiday decoration, H. helix is invasive and is a pathogen alternate host in British Columbia.
New Zealand H. helix has been listed as an "environmental weed" by the Department of Conservation since 1990.
United States 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, with its sale being banned in both states.USDA Plants Profile: Hedera helixOregon bans sale of English ivy, butterfly bushesControlling English Ivy . Northwest Coalition for Alternatives to Pesticides. 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.Controlling English Ivy Arlington County, Virginia Department of Parks, Recreation and Community Resources. Ivy can easily escape from cultivated gardens and invade nearby parks, forests and other natural areas via squirrels and birds.
Control, eradication, and recovery Once ivy is established it is very difficult to control or eradicate. If left untreated it will crowd out other ground cover plants and can choke out and kill shrubs and overstory trees.
Tested and successful methods of control are mechanical removal and chemical applications. Chemical eradication includes the use of 2,4-D amine, glyphosate, and metsulfuron, with metsulfuron being the most effective on H. helix. Mechanical removal typically involves hand pulling and has been found to be more environmentally beneficial in the long term than chemical removal. A study has shown that after removal, seed addition significantly increased species richness, diversity, and density on pulled ivy, while seed addition had no benefits on chemically sprayed ivy. This is likely due to the dead roots still occupying the soil after spraying, which are removed when pulling.
After mechanical removal, the recovery of native species can be significant after one year from resprouting and germination. However, ivy produces fruits that can be spread by birds, so continuous management after recovery is still necessary to prevent invasion from recurring in the same location or nearby.
One study found that during the next growing season after H. helix removal, herbaceous native plants were more abundant and diverse, while shrubs and ferns had either no increase or a decrease in abundance and diversity. This can be due to herbaceous plants having viable seeds buried in the soil, while ferns are slow-growing, and existing shrubs may not bear seeds from limited sunlight in the forest.
Areas of invasion can be identified using LiDAR detection, which has been measured at around 82% accuracy, with better accuracy in places with less canopy cover.
Damage to trees Ivy can climb into the canopy of young or small trees in such density that the trees fall over from the weight, a problem that does not normally occur in its native range. 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. It is also thought to be a reservoir for leaf scorch bacteria. However, the UK Woodland Trust considers that it does not damage trees and hence does not require removal. The ivy also blocks the sun from the trees that need it for photosynthesis.
Cultivation
Ivy 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.Plant for Wildlife: Common Ivy (Hedera helix)
In Europe, it is frequently planted to cover walls and the Bavarian government recommends growing it on buildings for its ability to cool the interior in summer, while providing insulation in winter, as well as protecting the covered building from soil moisture, temperature fluctuations and direct exposure to heavy weather. Further uses include weed suppression in plantings, beautifying unsightly facades and providing additional green by growing on tree trunks.
However, ivy can be problematic. It is a fast-growing, self-clinging climber that is capable of causing damage to brickwork, guttering, etc., and hiding potentially serious structural faults, as well as harbouring unwelcome pests. Careful planning and placement are essential.
Cultivars Over 30 cultivars have been selected for leaf traits such as yellow, white, variegated (e.g. 'Glacier'), and deeply lobed (e.g. 'Sagittifolia'), and other traits like purple stems and slow, dwarfed growth.
The following 16 cultivars have gained the Royal Horticultural Society's Award of Garden Merit:
'Angularis Aurea' 'Buttercup' 'Caecilia' 'Ceridwen' 'Congesta' 'Duckfoot' 'Glacier' 'Goldchild' 'Golden Ingot' 'Maple Leaf' 'Manda's Crested' 'Midas Touch' 'Parsley Crested' 'Shamrock' 'Spetchley' 'White Knight'
Toxicity and medical uses Ivy berries are somewhat poisonous to humans, but extracts from ivy leaves are part of current cough medicines.European Medicines Agency, Committee on Herbal Medicinal Products (2017). Assessment report on Hedera helix L., folium, pp. 5-16 A 2020 evidence review found that H. helix preparations "may be a therapeutic option for treating early symptoms of respiratory tract infections", saying that "the best effectiveness for H. helix preparations has been proven for coughing, as an expectorant and to reduce the frequency and intensity of cough. Only weak evidence was found for all other researched symptoms."
In the past, the leaves and berries were taken orally as an expectorant to treat cough and bronchitis.Bown. D. (1995). Encyclopaedia of Herbs and their Uses. Dorling Kindersley, London. In 1597, the British herbalist John Gerard recommended water infused with ivy leaves as a wash for sore or watering eyes. The leaves can cause severe contact dermatitis in some people. 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.