Common ivy, also known as English ivy or scientifically as Hedera helix, is a very common ivy found throughout Britain. It can be seen throughout the year, but flowers September-November. Its nectar, pollen and berries are all essential food sources for pollinating insects and birds, while its foliage provides shelter and habitats for other small mammals and insects.
Anatomy:
Common ivy is an evergreen, with glossy dark green leaves that have pale venation. They are a climbing plant, and have specialised ‘hairs’ on the stems, which are small aerial roots, which it uses to bind to the surfaces (e.g. tree bark, fences) it will climb. They can spread 2.5-4 metres wide and have an ultimate height of 8-12 metres; it takes 10-20 years to reach this height. They have palmate shaped leaves made from 3-5 lobes, however shoots that bear flowers have oval or heart shaped leaves that are lighter. These shoots are often found at the top of a tree, in direct sunlight where they can form flowers. The flowers appear in autumn, and have a yellow-green colour; made from five petals, five stamens, a central stigma and rudimentary sepals. The ovary contains five ovules which can become seeds. Over the winter months a berry (containing 3-5 seeds) will mature, appearing black and providing a food source for birds throughout spring.
Habitat:
This ivy is very common, hence the name ‘common ivy’, and can be found throughout Britain across woodlands, hedgerows and buildings. They are very hardy and can survive in many levels of sun exposure, from both full/partial sun to full/partial shade. They also grow in a wide variety of soil conditions, growing well in chalk, clay, sand and loam. Moreover, they can also grow in acidic, alkaline and neutral environmental conditions. They prefer moist but well drained soil, however have some drought tolerance.
Does ivy damage trees?
It is often misunderstood that common ivy directly damages the trees it grows on, with many misconceptions that it takes nutrients away from the trees of suffocates them. But is this really the case?
- The benefits:
Common ivy is not parasitic, deriving its own nutrients from the soil using its own root system. The aerial roots are only used to anchor the plant to the tree and do not damage the bark. They tend to be seen on trees that are already damaged or dying as healthy trees have too much cover, meaning light cannot get through the canopy for the ivy to successfully photosynthesise. However, it is not an indicator of an unhealthy tree. It is unlikely to be of competition to the trees in which it grows on as it mainly covers mature, well established trees. Ivy also has a lot of value to the wildlife; climbing ivy growing on trees provides a place to hide, roost, hibernate and nest in for small birds and insects such as butterflies and beetles. Common ivy that acts as ground cover reduces the effects of frost in the winter months which provides a place for these birds and insects, and small mammals, to gather warmth and forage when food in sparse.
- The problem:
Ivy becomes a problem when its growth gets out of hand, and becomes too heavy for the tree to support. As the trees it usually resides on are already declining, added weight may cause parts to snap off. Trees with thin, open crowns, such as ash and larch, may suffer from heavy infestation which may overwhelm the tree and prevent its own leaf growth by blocking the canopy. Trees that are grown for aesthetics, such as in parks or to sell, must be kept ivy-free as to not damage the bark; a key ornamental feature.
Toxicity:
Hedera helix is toxic to cats, dogs and horses when ingested and for safety, should be kept far away from our pets. It is, however, a very beneficial food source to caterpillars and its flowers are rice in pollen which attracts bees, insects, butterflies and moths. It also has seeds that are eaten by birds, and its foliage provides shelter and habitat. There is no reported toxicity to birds, livestock and people but it can cause contact dermatitis in humans. This is an allergic skin rash that has been noticed to occur on gardeners while rimming back ivy. Consuming ivy can also cause side effects, such as nausea, vomiting and diarrhoea. However, lack of research into this means little is known about the full extent of toxicity or safety of common ivy.
Potential health benefits:
H. helix contains the polyphenols, saponins and flavonoids which are effective anti-inflammatory and antioxidant compounds. This shows ivy extracts may be useful in treating inflammatory conditions and preventing excess cell damage. Furthermore, ivy has been reported to help with coughs, and may be useful in treating asthma, bronchitis, coughs (particularly in children, when traditional cough medicine can’t be used) and COPD. It is thought that the anti-inflammatory compounds in ivy may be the cause of this. Research has found that ivy may be able to activate the beta2-adrenergic signalling system throughout the body, this promotes the release of the compound epinephrine. This is acts as a bronchodilator, widening the bronchi and bronchioles which allows for increased air flow. Additionally, keeping this plant as a house plant may help improve the air quality as it is known to purify the air of smaller spaces. However, as previously stated it can be toxic to common household pets so caution must be taken if this plant is grown indoors.
Overall, there is not enough scientific research into the health benefits of consuming this plant and its level of toxicity so it should not be foraged and eaten from the wild.
Mythology:
The use of ivy in wreaths has a lot of symbolism, particularly in ancient Rome and Greece, and even in current times. The Roman god, Bacchus, was known as the god of intoxication and is often shown wearing a wreath of ivy and grapes. It became thought that wearing a wreath of ivy around the head prevented you from getting drunk. It was also known as a symbol of intellectual achievement in ancient Rome and became the wreath that was used to crown winners of poetry contests. Wreaths were also given in ancient Greece to winning athletes.
Wreaths were also given to newly married couples by the priest, as ivy was a symbol for fidelity. And even today it is still the custom to include ivy in bridal bouquets.
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