English ivy is certainly one of the most common and widespread invasive species on Salt Spring Island. I think we are all familiar with this fast-growing evergreen vine as a dense groundcover or tree climber.
English ivy was introduced from its native range of Europe as a groundcover for landscaping purposes. It has since escaped and spread quickly throughout forest understories, where it can grow as a dense mat that suppresses native plants, as well as climb trees, reducing their lifespan and leaving them more susceptible to wind damage. The stems of older vines can form roots up to five inches thick, which cling strongly to trees.
The leaves are star-shaped with 3-5 points, and are waxy or leathery to the touch. They are typically 5-10 cm long and 6-12 cm wide, and found in a range of colours from dark or silver green to yellow or white. Confusingly, the leaves on the fruiting stems are egg-shaped without points or lobes, wholly unlike the leaves on the rest of the vine. Unremarkable clusters of small white to yellow-green flowers bloom in late summer and early fall, followed by clusters of black shiny fruit. Spread by birds eating its berries, this vine also spreads easily by cuttings or layering.
Removal
The long vines creeping along the forest floor can easily be pulled up when the soil is wet – very satisfying! Cut vines away from tree trunks and at the bases to kill the vines above; spot application of herbicide can help kill the roots and prevent re-sprouting.
When removing English ivy from trees and other high structures, try your best to cut away as much of the vines as possible, as they can become fire ladders when dry, making them a significant fire hazard. Do not compost the vine or any of its parts, as they will re-sprout!
The Invasive Species Council of B.C. says it may require several years of mechanical control to eradicate English ivy, depending on the size of the area. If pulling the vines, wear gloves and a long-sleeved shirt, as they have been reported to cause skin rashes when handled. Bag and dispose of vines or burn them safely.
Plant These Instead
There are few native vine alternatives that compare to English ivy in its ability to cover and climb; however, here are some native groundcover alternatives. The orange honeysuckle and the hairy honeysuckle are the only vines that will grow in shade or semi-shade conditions similar to the English ivy; their flowers are beautiful and pollinator-friendly.
Wood Sorrel (Oxalis oregana)
Wood Sorrel is a perennial with clover-like leaves that open and fold according to light levels. The plant holds its leaves horizontally to maximize interception of light in the dim forest understory, and folds its leaves down in direct light or heavy rain, presumably to reduce the impact of the raindrops.
The flowers are unremarkable but charming: white to pale-pinkish with one per stem. This is an excellent plant for a moist, shady area in need of a groundcover.
Here’s what Master Gardeners’ of BC say: “It’s an edible weed, with a slightly sour, lemony flavour. It’s high in vitamin C. BUT BE AWARE that it (like spinach and many other edible plants) contains oxalic acid. It should NOT be consumed in LARGE QUANTITIES by people or livestock, especially people with kidney stones, rheumatism, or gout.”
Bunchberry (Cornus canadensis)
Bunchberry is a circumpolar species, preferring moist coniferous forests but also thrives in meadows and bogs, and will even grow up tree trunks or logs. Bunchberry does best in moist, acidic soils, and does not tolerate dry conditions for long.
It is a low, trailing, rhizomatous perennial with woody stems (technically a shrub), found in the Dogwood family. The white ‘flowers’ are in fact bracts with the true flowers blooming in the centre, framed by the bracts. Bright red berries form by the fall and hold on all winter with the semi-evergreen leaves turning from green to purples and reds. The berries are eaten by deer, quail, and some songbirds.
Wild or False Lily-of-the-Valley (Maianthemum dilatatum)
Another groundcover for moist and shady conditions, this perennial has creeping rhizomes, and can be a lovely addition to a woodland garden. Reaching 10-40 cm in height, False Lily-of-the-Valley produces several small white flowers per stem that are lightly fragrant and provide a food source for native moths. Birds eat the red berries in the fall.
Other Alternatives
- Kinnikinnick
- Evergreen Violet
- Wood Strawberry
- Oregon Grape
- Salal
- Black Twinberry
- Orange or Hairy Honeysuckle
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