Examining the English ivy

by Helen M. Scott
Wednesday, March 5, 2008 2:56 PM MST

Recently a particular plant caught my eye -- an English ivy.

This little beast, in the middle of January, was bright green and thriving in my neighbor's yard.

Research on this plant tells me this is a widely planted evergreen vine, hardy to Zone 5, and introduced as an ornamental into North America from Eurasia during colonial times.

As a garden escapee, however, this vine, under maximum growing conditions, can be quite invasive spreading into their neighboring forests in areas, such as the coastal regions from Oregon to British Columbia.

The English ivy has two distinctive growth stages - juvenile and arborescent. Juvenile plants grow along the ground, and arborescent or treelike forms are erect shrubs. It is this second form that causes significant environmental damage.

As an arborescent, English ivy can completely cover walls, buildings, roofs and trees. It is said that this extra weight often causes trees to topple when exposed to high winds.

On the ground, English ivy, because of its dense growth and abundant leaves, prevents light from reaching important native plants. Under the most conducive growing conditions, this amazing vine can reach heights of 50 meters and depths of one meter above ground.

Despite its invasiveness, English ivy is a much sought after ornamental plant, treasured for its attractive shapes, colors and habits. In fact, there are many advocates of this vine that are quick to point out its benefits.

These include providing shelter for bats, birds and invertebrates, along with nectar for insects. But it is indisputable that this ivy inhibits the growth and regeneration of native wildflowers, shrubs and trees through shading, smothering, and through associated harmful pathogens.

In British Columbia, for instance, the plant is widespread and is removed on sight.

As mentioned above, it exists in both juvenile and arborescent forms. The juvenile grows like a thick mat, choking out other plants. Crawling along the ground, the young vine extends until reaching a vertical face to ascent.

At this point, it turns and grows upwards along the face, using hairy rootlets to tightly adhere to rough surfaces. Once it can no longer climb, it stops and sends out tendrils without rootlets.

Soon after, the juvenile form transforms into an arborescent form, producing new rounded and smooth-edged leaves. Then it grows as a dense, heavy and stoutly branched shrub which can, if left uncontrolled, pose a threat to nearby trees and shrubs.

This mature form can produce flowers in the fall and fruits containing hard seeds in the spring. Seeds are mainly dispersed by birds such as robins and sparrows in milder climates. It also reproduces by vegetative cuttings or from stems contacting the ground.

However, this brings me to my point: sometimes gardeners in Wyoming need tough plants to be used in difficult areas in their gardens or yard - plants that are tough and adaptable that can provide protection from the wind.

The English ivy is a beautiful plant, and if you have a spot in your yard that needs green covering over a patio or an alley fence, or even old buildings, and have evaluated its invasive side, then utilize this plant.

It will only expose its most invasive nature grown under certain ideal climate conditions that exist in Oregon or British Columbia - not in Wyoming.

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