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Species
Hedera helix var. taurica
IUCN
NCBI
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.
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Rights holder/Author | Bob Press and Jacek, Natural History Museum |
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Europe, Western Asia and Northern Africa
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 |
More info on this topic.
More info for the terms: cover, frequency, phase, shrub, succession, tree
Shade tolerance: Several studies [32,49,62,132,136,150], reviews [51,97], and invasive plant publications [99,190] indicate that English ivy grows in a wide range of light conditions, from full shade to full sunlight. In general, the juvenile form of English ivy most often occurs in the shade [62,97], while the adult form occurs in full sun [32,99]. English ivy's tolerance to shade [32,51,99] has been described by one propagation manual as "legendary" [31]. English ivy's tolerance to full sun may vary and depend on the cultivar or site conditions [150,158]. English ivy's ability to adjust its photosynthetic capacity under variable light regimes may explain its tolerance to a wide range of light levels [62].
English ivy's photosynthetic capacity adjusts for variable light levels; to what degree may be determined by the life phase (juvenile or adult) of the plant [10,62,110]. In general, adult leaves have a greater photosynthetic capacity than juvenile leaves, even on the same plant [62,97]. Under experimental conditions, juvenile English ivy's capacity to accumulate light was not as well developed as its adult phase. Juvenile leaves, however, tolerated light and were not damaged by increased light [62]. English Ivy may respond quickly to changes in light level by temporarily increasing or decreasing photosynthetic rates. English ivy growing in the shade may undergo brief periods of photoinhibition in the winter when leaves of deciduous trees are shed. For English ivy growing in constant light, photoinhibition may be facilitated by low temperatures [110]. Grime [51] speculated that for juvenile English ivy growing in the shade, carbohydrate availability may depend more on energy conservation than accumulation efficiency.
In some locations, English ivy may reach its greatest abundance in shade. In France, English ivy reached its highest frequency in a floodplain forest on "dark" plots with less than 2.5% light transmission [142]. In experimental plots, English ivy cover grown in 60% shade ranged from about 10% to 70% during a 1-year period. During that same time, English ivy cover failed to reach 20% during any time of the year for plants grown in full sun [150].
Potential successional stage: English ivy's tolerance to a wide range of light levels suggests it may establish and/or persist throughout most successional stages. Information pertaining to English ivy's successional role in its North American range is limited. In forests that had been previously clearcut in western Oregon, English ivy was not present in seedling or sapling stands but occurred in mature stands (frequency <2%; cover ~2%) with large-diameter trees. Thinning mature stands had little effect on English ivy frequency (<1%) compared to unthinned stands (<1%), however, its cover was less in thinned stands (1.5%) than in unthinned stands (3.5%). English ivy frequency generally increased with increased tree canopy cover [50]. In Washington, DC, English ivy occurred in a deciduous forest that had not been logged for 102 years [43]. In a secondary piedmont forest in Georgia, English ivy persisted for at least 30 years (Carter personal communication cited in [11]). In a forest along the Bronx River Parkway in New York, it persisted for at least 25 years [44]. In another secondary piedmont forest in Washington, DC, English ivy displaced the groundlayer vegetation, previously dominated by Virginia springbeauty (Claytonia virginica), within 10 years of its establishment [170].
Several studies and publications from Europe describe English ivy's successional role in parts of its native range [38,56,76,121,135,168]. One long-term study from the United Kingdom indicates that English ivy's successional role may be highly variable. Researchers observed successional changes over 100 years in 2 secondary woodlands where English ivy occurred. The woodlands established on previously cultivated land that had been abandoned for about 20 years. Site 1 consisted of woodland and meadow plant communities and was first surveyed in 1886. English ivy was first observed in the woodland community on Site 1 in 1903. Over the next 53 years English ivy continued to spread, and by 1998 it formed a "dense carpet" in the woodland. In the meadow portion of Site 1, English ivy established in 1913 but was absent by 1945. While it was present during the 1951 and 1965 surveys, it was once again absent from the meadow in 1998. On Site 2, which was primarily a grassland with a few woody species, English ivy was not observed there until 1957, approximately 60 years after surveying began. While it persisted on Site 2 throughout the remainder of the study (1998), it did not dominate [56].
Other studies from Europe indicate that English ivy occurs in early to midsuccession; however, its abundance at any given stage may vary [38,76,121,135,168]. In England, English ivy is typically uncommon in woods except around edges. It establishes during the early stages of succession and may persist for centuries [38,121]. In a previously cultivated hay meadow in England that had been abandoned for 20 to 30 years, English ivy established during the "building phase" (average plant age 15-50 years) of plant community development [76]. In the Chiltern Hills in England, English ivy occurs in various stages of succession, but it is more frequent in early stages of oak woodland succession and in developing woodland [189]. In an oak forest in France, English ivy's frequency increased by 10% within 19 years [168]. In the United Kingdom, English ivy established in a field about 15 years after cultivation ceased and dominated the ground flora of a secondary woodland within 50 years [56]. Because English ivy seedlings establish and grow in both sun and shade (see Shade tolerance), it seems able to establish during early to midstages of succession.
Studies from Europe suggest that English ivy may persist into late succession. One literature review indicated that populations of English ivy that established in northern Eurasia during a global cooling period that ended about 5,000 years ago have persisted through vegetative reproduction [97]. In England, English ivy occurred in a woodland that had undergone selective logging but still contained 200-year-old trees [144]. Based on vegetation surveys in the Rhine Forest in France, researchers classified English ivy as a species adapted to highly fragmented, mid- to end-successional stages [135].
On sites where English ivy becomes dominant, it may influence succession. English ivy may inhibit regeneration of the understory, resulting in an English ivy- dominated community with few if any woody plants getting tall enough to form a shrub layer [170]. Because English ivy facilitates tree fall (see Impacts) and accelerates forest gaps [136,170], it may influence succession by creating canopy gaps.
Chile Central
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Rights holder/Author | Pablo Gutierrez, IABIN |
Source | No source database. |
More info for the terms: presence, shrub
Publications from the United Kingdom indicate that English ivy seed is short-lived and does not form a persistent seed bank [52,97]. Because English ivy's flowering and fruiting is limited by shade (see Pollination and breeding system), accumulation of English ivy seed in woodlands may be an "expensive luxury" [171]. Under experimental conditions, English ivy seed planted in various size containers and soil types continued to germinate for 1 year after planting; however, germination and seedling survival generally declined over time, particularly for seed buried 5 months or longer [152].
English ivy's presence in the aboveground vegetation may not indicate its presence in the seed bank. In deciduous forests in northwestern Greece [22] and Denmark [75], English ivy occasionally occurred in the aboveground vegetation but its seed was not found in the soil seed bank. In a deciduous forest in Spain, English ivy was 1 of 4 dominant shrub species in the understory (3% aboveground cover) but did not appear in the seed bank at samplings depths of up to 4 inches (10 cm) [112].
Barcode of Life Data Systems (BOLDS) Stats
Public Records: 29
Specimens with Barcodes: 50
Species With Barcodes: 1
More info for the terms: cover, density, liana, orthotrophic, phase, plagiotrophic, shrub, shrubs, tree, vines
This description covers characteristics that may be relevant to fire ecology and is not meant for identification. Keys for identification are available (e.g., [30,46,60,103,122]).
Aboveground: English ivy is a woody [184], evergreen [30,46,52,60,99,184], trailing or climbing liana [30,92] or shrub [129]. In Europe, English ivy occasionally grows as a tree [97,136].
English ivy has 2 distinct growth phases, the vegetative phase (juvenile) and the sexual reproductive phase (adult) [153].
Comparison of juvenile and adult growth phase of English ivy [153] | ||
Characteristic | Juvenile | Adult |
Growth habit | plagiotrophic | orthotrophic |
Flowers | absent | present |
Leaf arrangement | alternate | 2/5th spiral |
Leaf production | 1 leaf/week | 2 leaves/week |
Shoot growth | vigorous | slight |
Leaf shape | lobed | entire |
Rooting ability | good | weak |
Aerial roots | present | absent |
Individual English ivy plants may have both juvenile and adult stems. The juvenile phase typically forms the ground cover [31,99]. Juvenile English ivy begins to climb when vertical structure is available (e.g., trees, shrubs, buildings, utility poles), and vertical stems transition to the adult phase [97].
As a ground cover, English ivy grows from 6 to 8 inches (10-20 cm) tall [31,99]. Once stems begin climbing, they typically reach 90 feet (30 m) in height [25,31,46,65,99,152,184] but occasionally may climb higher, reaching the tops of 300-foot (90 m) conifers [146]. English ivy climbs with the aid of root-like structures [19,25,31,46,84,152] that exude an adhesive substance [99]. One publication from England indicated that English ivy attaches to substrates by numerous small roots [52]. Branches are typically slender on low-growing plants [99], but climbing and older trailing branches may be 4 [31,135] to 12 inches (10-30 cm) in diameter [25,65,99,146,152], with furrowed bark [31]. Leaves are typically 4 inches (10 cm) long × 2.5 to 5 inches (6.4-13 cm) wide and are 3 to 5 lobed in the juvenile phase and broadly lanceolate and unlobed in the adult phase. Flowers are clustered in umbels on adult stems [99]. There are 8 [182] to 20 [97] flowers/umbel; umbels grow in clusters of 3 [97] to 6 [14]. English ivy fruit is a berry [30,60,104] about 5 [186] to 9 mm long [60,122] and 6 [192] to 9 mm in diameter [145], with an average weight of 281.5 mg [59]. Its fruit contains 2 to 5 seeds [30,31,59,60,145,184] that are about 5.7 × 3.7 mm in size [52].
Belowground: Information from an exotic pest website in the Southeast suggests that English ivy does not form an extensive underground root system [149]. An invasive plant publication from California [126] and a publication suggesting landscaping plants for use in chaparral plant communities to reduce fire hazard [123] suggests that English ivy's roots are generally shallow. In Washington, DC, English ivy root depth ranged from 1 to 4.13 inches (3.0 -10.5 cm) below the soil surface [169]. A study from Spain measured rooting depth for several vines including English ivy and found the average rooting depth for all species was statistically similar (P<0.001); root depth for 100 mg of plant dry mass was 3.8 inches (9.6 cm), and for 1.00 g of plant dry mass it was 6.34 inches (16.1 cm). English ivy roots were highly dissected, and the average root diameter 5 mm from the root tip was 0.45 mm [133].
Stand structure: In woodlands, English ivy frequently forms a dense ground cover that may occupy large areas made up of numerous individuals [97]. In North America, English ivy has been described as forming an "ivy desert" [125]. In the Green River Gorge in North Carolina, English ivy completely covered the ground in a deciduous forest [120]. In floodplain forests along the Rhine River in France, English ivy "carpets" the forest floor until it eventually reaches a tree and begins to ascend [135]. In one study in these forests, average English ivy stem density was 24.5/ha on sites that experience brief annual flooding compared to 61.9/ha on sites where flooding had been excluded. Clumping (more than one English ivy vine/host tree) was common, particularly on trees in the canopy and subcanopy of the forest, largely due to the greater abundance of support in these layers [136]. In another study in the Rhine River floodplain in France, English ivy stem density reached 120 stems/ha in a dense Lombardy poplar (Populus nigra) and English oak forest [135].
Longevity: As of this writing (2010), information pertaining to English ivy's longevity in North America was lacking. In forests along the Rhine River in France, the oldest English ivy vines at 1 site were 50 years old, while the oldest vines at another site were at least 66 years old [136]. There is a report of a 433-year-old stem of English ivy that was over 20 inches (60 cm) in diameter, but it is unclear where it occurred (Schenk 1893 cited in [37]).
More info for the term: phenology
English ivy seed is dispersed by birds [25,60,99,146,159]. In North America, birds that distribute English ivy seed included European starling, cedar waxwing, American robin, Steller's jay, mockingbird, and house sparrow [160]. Snow and Snow [145] provide a list of birds that may act as potential dispersers of English ivy seed in the United Kingdom (see IMPORTANCE TO LIVESTOCK AND WILDLIFE). After digesting the fruit, birds may regurgitate English ivy seed one at a time [23]. One literature review suggested that English ivy seed is deposited in bird droppings as well as regurgitated [97]; however, a seed germination study found no evidence that English ivy seed is defecated by birds [23]. Researchers in the Netherlands speculated that English ivy has an 80% chance of being dispersed to a forest if there is a seed source 3 feet (1 m) or less away, but at 3,000 feet (1,000 m) away, the probability decreases to nearly 0% [48].
English ivy phenology may vary for different locations and influence the dates when seed becomes available for dispersal [145]. In the United Kingdom, English ivy seeds are dispersed in early winter (November and December), but early flowering plants likely have their fruit taken sooner [97,145]. In Germany, English ivy seed was dispersed in later spring (Kollman 1994 cited in [76]).
Canada
Rounded National Status Rank: NNA - Not Applicable
United States
Rounded National Status Rank: NNA - Not Applicable
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