Atlantic ivy or Irish ivy
Hedera helix (syns. Hedera helix ssp. helix, Hedera canariensis, Hedera helix ssp. canariensis)
Hedera hibernica (syns. Hedera helix ssp. hibernica)
English ivy is an evergreen climbing vine in the Araliaceae (Ginseng) family. It has historically been a common garden ornamental and has more than 400 cultivars. It has escaped cultivation to become highly invasive in forests and natural areas throughout the Pacific Northwest. Native to Europe, these plants are characterized by long viny stems reaching up to 30 m in length, with aerial, clinging small root. English ivy damages desirable vegetation by shading out and smothering plants. English ivy also covers trees making them more susceptible to wind fall due to the additional weight of the ivy in the trees as well as the additional drag of the evergreen leafy vines.
Height of mature plants
This vine climbs into the canopy of mature trees and so can grow very high.
Typically blooming during months when not in a purely vegetative state.
In Oregon, three Hedera species have been documented: English ivy (H. helix), Atlantic ivy (H. hibernica), and Persian ivy (H. colchica). However, only English and Atlantic ivy are listed as noxious weeds in Oregon. The invasive plant commonly referred to as English ivy is actually comprised of both English ivy and Atlantic ivy. Identification and differentiation between the species is complicated because there many cultivated varieties. Both English ivy and Atlantic ivy have been commonly sold as English ivy, but can be differentiated by leaf shape and tiny hairs on the young leaves. These two species can also be differentiated through genetic testing.
The areas most infested by English ivy are urban natural areas, disturbed forests, woodlands, and along stream corridors. Plants grown in moist soils with summer shade and winter sunlight will flourish. Urban forest and natural areas are especially impacted as a result of repeated reinfestation from garden escapees.
Rapid and massive vegetative growth of English ivy vines reaches to treetops and woody ornamentals. It also can displace native vegetation on the forest floor. English ivy frequently becomes intertwined with forest shrubs creating difficulties for manual removal or herbicide use. Removal costs in some Oregon parks have reached $3000 per acre.
Noxious Weed Listing:
- WeedWise: Maintenance
- State of Oregon: Class B
- State of Washington: Class C
- Four County CWMA: Class C