British Wildlife Wiki

Quercus ilex, the Holm Oak is a large evergreen oak native to the Mediterranean region. It takes its name from holm, an ancient name for holly.


Quercus ilex is a medium-size tree 20–27 m tall with finely square-fissured blackish bark and leathery evergreen leaves. The old leaves fall 1–2 years after new leaves emerge. The leaves are dark green above and pale whitish-grey with dense short hairs below. The leaf shape is variable, the adult leaves are entire, 4–8 cm long and 1–3 cm broad, while those on the lower branches of young trees are often larger (to 10 cm long), and are toothed or somewhat spiny - possibly as protection from grazing animals. In this, the foliage resembles that of the common European Holly Ilex aquifolium, and this resemblance has led to its common and botanic names. The name ilex is originally the classical Latin name for the Holm Oak, but was later also used as a botanical genus name for the hollies. The flowers are catkins, produced in the spring; the fruit is an acorn, which matures in about six months.


Holm oak is damaging biodiversity in the United Kingdom, and is listed as an alien invader. Normally the tree is unable to withstand frost, which would normally prevent it from spreading north, but with climate change, it has successfully penetrated these areas.