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Invasive Species |
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Tree Killers
English Ivy
(Hedera helix)
 Photo 19: John M. Randall/The Nature Conservancy Biology
- evergreen climbing vine with waxy, dark green, white-veined leaves
- belongs to the Ginseng family
- attaches to trees by sticky rootlets that develop along the stem
- vine stems can be up to 30 cm (12 in) in diameter and can climb to 30 metres (100 ft) in the canopy
- reproduces by seeds contained in black berry-like fruits
- birds eat the berries and are responsible for long-distance spread of English Ivy since the seeds within the fruit pass through the bird without damage
- can reproduce vegetatively from broken or cut vines that root easily
- leaves contain a toxin which prevents most browsing
- prefers open woods
 Photo 9: Bill Jacobs/The Nature Conservancy History in Canada
- introduced as an ornamental from Europe
- still widely available from nurseries
- established in southern Ontario and southern British Columbia
Impact on Trees
- can grow in dense patches in open woodland, forest openings, and forest edges
- can form a thick, evergreen, ground cover that suppresses native tree seedlings
- can engulf and kill lower branches of trees due to heavy shade
- the extra weight of the vines and evergreen leaves causes the host tree to be much more susceptible to blow down from winds or heavy rain, snow, or ice
- may harbor a plant disease called Bacterial Leaf Scorch (Xylella fastidiosa), that harms elms, oaks, and maples
 Photo 21: Forest and Kim Starr, USGS, Hawaii Control
- cutting stems followed by herbicide application to the cut stems
- herbicide application to the entire vine
- several years of control may be needed since the seeds are unaffected by the above methods and seedlings can recolonize an area
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