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   Hedera helix (vine, climber)     
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      Hedera helix foliage (Photo: Chuck Bargeron, The University of Georgia, www.forestryimages.org) - Click for full size   Hedera helix flower (Photo: James H. Miller, USDA Forest Service, www.forestryimages.org) - Click for full size   Hedera helix fruit (Photo: James H. Miller, USDA Forest Service, www.forestryimages.org) - Click for full size   Hedera helix covering a large oak tree (Photo: Randy Cyr, GREENTREE Technologies, www.forestryimages.org) - Click for full size   Hedera helix infestation (Photo: Chris Evans, The University of Georgia, www.forestryimages.org) - Click for full size
    Taxonomic name: Hedera helix L.
    Synonyms: Hedera helix f. arborescens, Hedera helix f. minima, Hedera helix var. conglomerata, Hedera helix var. crenata, Hedera helix var. minima, Hedera helix var. taurica, Hedera poetarum var. taurica, Hedera taurica
    Common names: English ivy (English)
    Organism type: vine, climber
    Hedera helix is an evergreen climbing vine of the ginseng family (Araliaceae). It 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. It is widely used as a fast-growing, low maintenance, evergreen groundcover and once established at a site, Hedera helix can be expected to move beyond its intended borders by vegetative means or by seed. Seeds are dispersed to new areas primarily by birds.
    Description
    Diedrich and Swearingen (2000) describe Hedera helix as an evergreen climbing vine in the ginseng family (Araliaceae). Leaves are dark green, waxy, somewhat leathery, and arranged alternately along the stem. H. helix has many recognized leaf forms. The 3-lobed leaves occur on the juvenile plant, which climbs by means of adventitious roots. After reaching a certain size (age?), and usually when it grows tall enough to get into the sun, the plant assumes its mature form, with unlobed, oval leaves. This form does not climb. The process is not reversible, and cuttings from the mature form remain mature. In fact in cultivation they can be trained into small (non-climbing) shrubs or trees (Thompson, K., pers.comm., 2004). Umbrella-like clusters of small, greenish-white flowers appear in the fall if sufficient sunlight is available. Fruits mature in spring and are black with a fleshy outer covering enclosing one to a few hard, stone-like seeds.
    Similar Species
    Hedera colchica, Hedera helix cvs.

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    Occurs in:
    coastland, estuarine habitats, natural forests, planted forests, riparian zones, urban areas, wetlands
    Habitat description
    Diedrich and Swearingen (2000) state that Hedera helix requires temperate to subtropical climates where it infests woodlands, forest edges, fields, hedgerows, coastal areas, salt marsh edges, and other upland areas, especially where some soil moisture is present. H. helix will grow in variable light conditions but prefers shade, damp soils, and a moist, cool environment.
    General impacts
    According to Diedrich and Swearingen (2000), Hedera helix 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. The impacts of H. helix include decrease in native vegetation and loss of biodiversity. The dense growth and abundant leaves, which spring from the stems like small umbrellas, form a thick canopy just above the ground and prevent sunlight from reaching other plants.

    Vines climbing up tree trunks spread, surround and cover branches and twigs, preventing most of the sunlight from reaching the leaves of the host tree thus reducing photosynthesis. It cover meristems, and thus disrupt the tree's growth, first on branch tips and eventually at the tree top. The impacts on photosynthesis and growth may well produce parallel damage to the root system, since the tree can no longer provide the level of nutrition to the roots (David L. Morgan in Aliens-L January 28 2005). Loss of host tree vigor, evident within a few years, is followed by death a few years later. The added weight of vines makes infested trees susceptible to blow-over during storms.

    Uses
    H. helix is widely used by homeowners, horticulturists, landscape contractors, parks departments, and others who desire a fast-growing, low maintenance, evergreen groundcover as an alternative to lawn grass (Diedrich and Swearingen, 2000).
    Geographical range
    Native range: Diedrich and Swearingen (2000) state that H. helix is native to Europe, western Asia, and northern Africa. H. helix is one of the most abundant and widespread invasive plants in the United States. It has also invaded South America, Australia, New Zealand.
    Introduction pathways to new locations
    For ornamental purposes: H. helix has been used extensively in many parts of the United States as an ornamental landscape plant (Okerman, UNDATED).
    Landscape/fauna "improvement": H. helix has been used extensively in many parts of the United States as an ornamental landscape plant (Okerman, UNDATED).


    Local dispersal methods
    Consumption/excretion: Diedrich and Swearingen (2000) indicates that H. helix seeds are dispersed to new areas primarily by birds.
    In England the typical consumer is the blackbird (Turdus merula), a much larger bird than the house sparrow.
    For ornamental purposes (local): H. helix has been used extensively in many parts of the United States as an ornamental landscape plant (Okerman, UNDATED).
    Garden escape/garden waste: Once established at a site, English ivy can be expected to move beyond its intended borders into neighboring yards, parks and other lands, either by vegetative means or by seed (Diedrich and Swearingen, 2000).
    Management information
    Integrated management: According to Diedrich and Swearingen (2000), several effective methods of control are available for H. helix, including chemical and non-chemical, depending on the extent of the infestation, the amount of native vegetation on-site, and available time and labor. Vines growing as groundcover can be pulled up by hand, with some difficulty, and left on-site or bagged and disposed of as trash. Vines climbing up into the tree canopy are more difficult to manage. First, vines should be cut at a comfortable height to kill upper portions and relieve the tree canopy. Because H. helix is an evergreen vine and remains active during the winter, herbicide applications can be made to it any time of year as long as temperatures are above12 or 15 degrees Celsius for a few days. The systemic herbicide triclopyr (e.g., Garlon) is absorbed into plant tissues and carried to the roots, effectively killing the entire plant in place. Repeat herbicidal treatments are likely to be needed and follow-up monitoring should be conducted to evaluate the success of treatments.
    Reproduction
    Diedrich and Swearingen (2000) indicates that H. helix reproduces vegetatively and by seed, which is dispersed to new areas primarily by birds. New plants grow easily from cuttings or from stems making contact with the soil.
    Lifecycle stages
    During the juvenile or non-reproductive stage, Hedera helix is typically a ground cover. The leaves of the adult or reproductive form are usually a lighter green, thick, ovate to rhombic in shape and have less prominent whitish veins. During the adult stage, H. helix produces terminal clusters of greenish-white flowers in the fall, which are pollinated by wasps, bees, and flies. The following spring H. helix produces a dark purple, fleshy drupe (fruit).
    Reviewed by: Dr Ken Thompson Department of Animal and Plant Sciences The University Sheffield UK.
    Compiled by: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
    Last Modified: Wednesday, 16 November 2005


ISSG Landcare Research NBII IUCN University of Auckland