As autumn turns to winter and the last leaves fall from the trees, the abundance of ivy throughout the country becomes even more obvious. As well as trees it also clothes walls, rocky cliffs, masonry and electricity poles. It is one of the most misunderstood of Irish plants, and I frequently have to explain to people that it does not “strangle” trees or “suck the life out of them”. The language that people use for these fascinating plants is reminiscent of the descriptions of plague or murdering invaders.
Ivy is a native Irish species that can tolerate dense shade and often covers the ground where other light-loving plants cannot survive. But, like all green plants, ivy needs sunlight for photosynthesis so it uses its flexible stem to climb the trees towards the sun. Twisting around it climbs into the canopy and can form great clusters of evergreen leaves there that change the profile of the tree. But the roots of the ivy remain in the ground and the host tree is not harmed by its passenger. It merely provides the climbing frame.
The cover of ivy stems and its dark leaves are used by woodland birds for nesting in spring and by bats for roosting in the daytime. In autumn, when many other plants have fruit, ivy produces its yellow-green flowers, essential food for pollinators. An insect species called the ivy bee, new to Ireland, has just arrived in the southeast of Ireland and can be seen on sunny days feeding on the newly opening flowers of the ivy. The flowers are followed in late winter by clusters of black ivy berries, an important food resource for birds when foraging is difficult.
Like many other evergreens, ivy was believed in country folklore to symbolise eternity. It prompted people to believe in everlasting life and resurrection after death.
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However, Risteard Mulcahy, a retired heart surgeon, started a crusade against ivy in his book For Love of Trees which made a persuasive but flawed case against what he saw as ivy’s disfigurement of roadside and specimen trees. He believed that ivy cripples and deforms trees leading to their “premature death”. He made no reference to any objective scientific assessment and even admitted that “the prejudice I have about the effects of excessive growth of ivy on trees and hedgerows is largely based on my own observations”. In fact, there is no scientific evidence that ivy harms its host trees.
Also much-maligned is the honeysuckle, one of the first woodland plants to come into leaf in spring. The rich scents from its creamy yellow flowers in the summer are hard to resist. More attractive than ivy to the wild flower enthusiast, honeysuckle is also a tree climber. But, while ivy clings tightly on to the bark with aerial roots, honeysuckle grows more like a bean, twining itself through the branches to reach the light.
The old name of woodbine describes the tangled, binding nature of the honeysuckle. It does most of its growing before the tree canopy blocks out the sunlight. Honeysuckle was once regarded as a symbol of fidelity and affection. A person who wore honeysuckle flowers, with their sweet scent, was believed to dream of their true love. The flowers are a source of nectar for many insects by day and especially for moths at night.
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Honeysuckle brought out some colourful language from the writer John Stewart Collis in his classic book The Worm Forgives the Plough. Born in Dublin, he worked on farms in England during the second World War where he found himself clearing and thinning a woodland in Dorset.
He wrote: “I have come upon portions of the wood where honeysuckle has practically taken over: the captive, the twisted, the mutilated, the dying, the dead ash trees stood hopelessly entangled in the network of ropes, pulleys, nooses, loops, ligatures, lassos which outwardly appeared as lifeless themselves as a piece of cord, but were centrally bursting with life and power, ready and willing to pull down the wood.”
This, of course, is a huge exaggeration. Although the honeysuckle can mark the bark, it does not cause the “merciless throttling and strangulation” of trees that Collis claimed.
Some people think that wild climbing plants are untidy and this gives them a bad press most of the time. But these are important native species, and all have an important role to play in the woodland community. I have taught myself to love them.
Richard Nairn is an ecologist and writer. His most recent book Wild Shores is published by Gill Books
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