Flora and fauna: Opinion split over damage done by ivy
Ivy (Hedera helx)
IVY is a plant of contention, causing anger or pleasure wherever it grows.
It belongs to the family Araliaceae – the -ivy and ginseng family – and is the only true liana (climber), a tropical trait, found in Britain.
It is also dimorphic, having two distinct growth phases.
Phase one is the juvenile, trailing form with the familiar pointed leaves and aerial roots which will attach to any surface – stone, bark, even marble – enabling it to cling and climb.
In woodland or in gardens it is the perfect ground cover, but given any support at all, out come the roots and up, up and away.
Phase two happens when the plant has grown into the sunlight. Now the stems are thicker and rootless.
The leaves change from “ivy-shape” to ovoid, as in the illustration, and the flowers appear. These are not showy, and are produced in late summer, providing a valuable source of nectar for insects when other flowering plants are fading.
The berries, which ripen after the winter solstice, are black and very nutritious for nesting birds in spring.
Opinion is fiercely divided on the damage ivy does to trees, but you only have to see a dead tree completely smothered by it to realise that it must have some effect.
Ivy may not penetrate or parasitise the host, but it competes with it for water, nutrients and light.
Anyone who has stripped ivy will end up coughing from the collected dusty matter. Trees breathe through pores, or lenticels, in the bark, and these must get blocked by the detritus. So, lovely as ivy is, out of control it is certainly damaging.
Medieval herbalists believed that ivy counteracted the effects of alcohol simply because it was so frequently seen choking grape vines.
Drinking vessels were often made from ivy wood, or engraved with ivy, either to prevent the effects of over indulgence or to protect against bad or even poisoned wine.
Ivy and drink became so entwined that ivy covered poles were used to advertise taverns.
Pliny observed that the young yellow ivy berries prevented drunkenness, and Culpeper wrote: “The speediest cure for a surfeit by wine is to drink a draught of the same liquor wherein a handful of bruised ivy leaves have been boiled.”
There is some evidence that ivy leaves can remove corns and verrucas but, sadly, little proof that it cures a hangover.
Dr Richard Warren is a botanist from Barnard Castle