17 Dec What Tree? Common Holly
Common Holly (Ilex Aquifolium)
This month we focus on a common tree that is steeped in folklore and mythology and is commonly associated with Christmas – hence it being this month ‘What Tree?’.
This evergreen species is native to the UK, Europe, North Africa and western Asia. It is common in woodlands, hedgerows and can also be found as open-grown field specimens too. It can grow up to 15m in height and live for over 400 years.
It is a medium-sized evergreen tree, which is relatively slow-growing, and notoriously hardy. The most distinguishing feature is the characteristic green prickly leaves and bright berries during winter.
The etymology of both the common name and Latin links directly to the prickly leaves found on this tree. The word Holly is derived from the Old English word ‘holegn’ which has a literal meaning of ‘to prick’. This ties with the latin ‘aquifolium’ which means ‘prickly’. With the genus ‘Ilex’ deriving from the Latin for Holm Oak (Quercus ilex).
Holly was historically used to decorate homes during winter, and this is a tradition that continues today with wreaths and garlands. Pre-Victorian times ‘Christmas tree’ literally referred to holly bushes and Christian symbolism connects the spiny leaves with Jesus’ crown of thorns, with the berries associated with drops of blood.
This species was associated with thunder gods Thor and Taranis and so people planted them outside the home to protect them from lightening. Amazingly more recent research has shown the spines on the Holly leaf actually act as miniature lighting conductors protecting the tree and objects nearby.
The holly is also seen as a fertility symbol and was used to wards against witches, goblins and devils. Interestingly, hedgerow trees were often omitted from trimming and left as standards to prevent witches from running along the top of the hedge. The felling or uprooting of holly trees was prohibited and the practice of taking cuttings was a permitted practice.
In order to ensure trees were not felled, trees were cultivated for fodder for livestock through the process of pollarding. Cutting the tree from horseback prompted regrowth from the pollard head with the arisings being fed to cattle during winter. There are ancient specimens found in Shropshire which provide direct links to this practice.
Holly trees are a commonly found in hedgerows. Not only does the dense foliage and leaf spines minimise the likelihood of livestock pushing through the hedge, but they also provide dense cover and food for nesting birds. Birds and small rodents feed off the berries during winter. However, if ingested by humans can cause stomach cramps, vomiting and diarrhoea.
The wood of holly is brilliant white, fine-grained and very durable. Due to the growth habit of this species, generally multi-stemmed and overall small in stature, the timber from holly is only used by furniture makers and engraving or wood carving.
Appearance and Identification
This species is easily identifiable by the characteristic prickly leaves and red berries during winter.
The leaves are dark green, leathery, shiny and have strong spines/spikes/prickles along the edge of an undulating leaf. The leaves are typically 5-10cm long and up to 5cm broad. The underside of the leaf is often paler.
You can often find mature trees, or the upper leaves of holly, are less spiny. With spiny leaves associated with young trees or lower foliage, often thought a natural defence to browsing.
This species is dioecious which means that male and female flowers grow on separate trees. The tree has small, dull white flowers in spring, which are followed by bright red berries on pollinated female plants.
Due to the evergreen nature of the tree, the distinguishing features of the bark are often overlooked, but it is typically smooth-grey with small grey-brown ‘warts’ in maturity.
The common holly can sometimes be confused with one of several variegated species of the tree (such as Golden King, Agentea marginata, silver queen etc.). These are generally distinguished by light colouring at the edge of the leaf or slight light discolouration of the entire leaf.
Propagation and Control
Holly is a particularly hardy species and can survive in a wide range of soil conditions (including various pH levels) and is also frost tolerant. It grows best in a well-drained soil and in full sunlight. However, it is shade tolerant and is often found as an understorey in native woodlands.
It is considered a pioneer species and is one of the first tree species to grow in cleared woodland areas, where holly was previously present. While the tree provides colour all year round, due to the spiny leaves and poisonous berries, it is rarely planted in urban areas, except as a natural deterrent or for habitat value.
This species has few pests or diseases, but it can suffer from leaf blight and miner. Holly leaf blight (Phytophthora ilicis) exhibits as black or purple blotches at the edge of leaves. Affected leaves generally drop prematurely and symptoms are visible after cool wet periods. Interestingly, this fungus-like organism was the subject of Steve’s final Masters dissertation. This research found that induced climatic conditions, in line with future predictions, will likely increase the prevalence of infection and impact on trees.
Holly can also suffer from holly leaf miner. The larvae can cause discoloured blotches by feeding along the leaf margins. This can often be confused for leaf blight but has minimal long-term impact to the tree other than visual discolouration of leaves.
Source and Reference Materials
Information detailed in this post has been obtained from the author’s own knowledge and photographic library where possible. Additional source of information and photographs include:
More, D & White, J. (2013). Illustrated trees of Britain and Europe. Domino.
Van den Berk, B.V. (2004). Van den Berk on Trees. Van den Berk Nurseries