Ivy, Hedera helix is a native climber common to most areas of the British Isles. It is not native to Scotland but pollen has been found in interglacial deposits indicating it was once part of the flora. Hedera is the name that has been used for Ivy since ancient times and the species name helix is derived from the Ancient Greek to twine and the Latin word ‘helium’ meaning spiral-shaped.
In folklore the climber was held in high esteem and was seen as a sign of eternal life, probably attributable to the fact that it will remain green and continue to grow after its supporting tree has died. The Romans dedicated the plant to the god Bacchus and it was considered that if an Ivy wreath was worn before imbibing alcohol it prevented intoxication, also bruising and gently boiling the leaves in wine acted as an antidote, however, as it is mildly poisonous to humans the practice is no longer used!
Hedera helix, exists as two main subspecies,
H.h. subsp helix, Common or European Ivy and H.h.subsp hibernica, Atlantic Ivy. These two subspecies are hard to distinguish, the species naturally showing a great deal of variation, but they are clearly distinguishable by their chromosome numbers ( the former being diploid whilst the latter is tetraploid having twice the number).
In this overview I will focus on an overall description of the species Hedera helix.
Hedera helix is an evergreen, woody, perennial climber, although it can be found in a bush like structure. Supports used for climbing are trees, walls, rocky outcrops and it is common in woodland, scrub and hedgerow. The stems in contact with the ground develop roots for feeding and absorbing nutrients, whereas smaller numerous roots which develop on the underside of the stem, away from the light are used to support the plant. These adventitious roots arise at the nodes on the stem (where the leaves meet the stem) and have small pads at the end which mould themselves to the crevices on the supporting structure and are only used to climb, Ivy is not a parasite.
It is able to reach great heights and is found clothing trees up into the canopy, or on the outside of buildings, walls and rocky outcrops. It can reach a great age and if undisturbed woody stems may get to a diameter of 30cm at the base.
There are two leaf types varying in size between 50 – 100mm long with a petiole (leaf stalk) which develop alternately on the stem; the juvenile leaf is palmate (shaped like a hand) with five lobes whilst the leaves on the fertile branches are unlobed and cordate (shaped like a heart).
Fertile stems (those able to bare flowers and fruit) only form where the plant is exposed to a higher light intensity. Flowers are borne on these stems from late summer to late autumn in cluster of 3-5 (umbels). They are a high nectar source for a large number of insects. Flowers are followed by fruits 6-8mm in diameter and varying in colour from purple – black to orange – yellow, these stay on the plant into the winter and provide an excellent source of food for birds. Small mammals and deer can also benefit from Ivy as a food source while it also provides excellent cover from predators.
Painting courtesy of Ann Swan – Atlantic Ivy – coloured pencil.
Elaine Allison – February 2019