hibernica – Ireland (Latin)

Native range: W. Europe

Leaves:

• alternate
• young leaves 3–5 lobed
• adult leaves (on vertical structures) ovate
• both entire
• long petioles
• prominent veins

Flowers:

• branched inflorescence (umbellate raceme)
• only adult plant flowers (when upright) after 15 to 20 years
• flowers in the fall

Fruit:

• clusters of small yellow-green flowers are followed (by usually) black round berries
• fruits in the spring
• foliage of flowering shoots is often less deeply lobed than that of the sterile, climbing shoots

Other characteristics:

• low shrub or vine
• creeps on ground or climbs trees
• evergreen

Relevant info:

• HIGHLY INVASIVE in PNW
• seeds spread by birds, then plant spreads vegetatively
• many non-invasive cultivars available
• the nomenclature is confusing…
  • four cultivars of English ivy have been shown to be most invasive in the Pacific Northwest and are Class C noxious weeds on the Washington State Noxious Weed List:
    • Hedera helix ‘Baltica’
    • H. helix ‘Pittsburgh’
    • H. helix ‘Star’
    • H. hibernica ‘Hibernica’
  • H. hibernica used to be classified as a subspecies of H. helix
  • it is also called Atlantic or Irish ivy but is very similar to English ivy and is generally called English ivy here
  • these invasive cultivars of ivy are on the non-regulated noxious weed list in King County
    • property owners are not required to control these species because it is well established in the region
  • much of what is invading here is called English ivy (H. helix) but is actually H. hibernica

Ecology & Adaptations:

• native in W. Europe, including British Isles, to Central Spain
• sea level to 500+ m.
• invasive in the PNW and must be managed in natural areas and restoration sites
• evergreen and well-adapted to the mild Pacific Northwest climate, it grows all year round in western Washington and can out-compete many other plant species
• very shade tolerant
• vegetative reproduction – spreads outward through its long vines that root at the nodes and climb over/around obstacles
• sexual reproduction – upon reaching maturity, it shifts to forming branches that produce berries
• seed dispersal – berries are distributed mostly by birds such as starlings, European house sparrows, band-tailed pigeons, robins and cedar waxwings, though berries are poisonous to some birds (i.e., have chemical herbivory defenses)
• control:
  • physical removal of English ivy vines and roots is often the most effective method of control
  • older thicker plants require more effort to remove
  • ivy growing up tree trunks can be controlled by removing all the vines from the lower trunk of the tree
  • ivy should be cleared from around the base of the tree as well, and the area should be mulched to resist re-invasion by ivy and other weeds
  • spraying young leaves with a systemic herbicide when the plant is actively growing is effective