Quercus ilex, also known as the Holm Oak or Holly Oak, is a large evergreen oak that is native to the Mediterranean region. It gets its name from holm, an ancient name for holly. This tree belongs to the white oak section of the genus and produces acorns that mature in a single summer.
The foliage of the Holm Oak bears a resemblance to that of the European holly, which is why it is commonly referred to as the Holly Oak. It is also known by its botanical name, Quercus ilex. In England, the first trees grown from its acorns can still be found in the beautiful grounds of Mamhead Park in Devon.
An evergreen tree of considerable size, the Holm Oak can reach a height of up to 28 meters (92 feet) in favorable conditions. It has a massive head with densely leafy branches that can span a significant distance. The trunk of this oak can measure over 6 meters (20 feet) in circumference. The young shoots of the tree are covered in a soft, grey felt-like substance.
The leaves of the Holm Oak are highly variable in shape, ranging from narrowly oval to ovate-lanceolate. They are typically 4-8 centimeters (1.6-3.1 inches) long and 1.2-2.5 centimeters (0.5-1 inch) wide. The upper surface of the leaves is a dark glossy green, while the lower surface turns grey or tawny.
Quercus ilex produces small acorns that grow in clusters of one to three. The acorns have a short, downy stalk and usually measure 12-18 millimeters (0.5-0.7 inches) in length.
There are two subspecies of Quercus ilex. The native northern and eastern range of the species is home to Quercus ilex subsp. ilex, which has narrow leaves and bitter-tasting acorns. Quercus ilex subsp. rotundifolia, which is native to the southwest of its range, has broader leaves and sweet-tasting acorns.
The Holm Oak is commonly found in pure stands or mixed forests in the Mediterranean region. It grows at low or moderate elevations and can be found in coastal areas from Portugal to Greece. This oak is particularly prevalent in the holm oak/Atlas cedar forests of the Atlas Mountains. In the United Kingdom, the Holm Oak is considered an alien invader and is damaging native biodiversity.
Despite its invasive tendencies, the Holm Oak has several uses. Its hard and tough wood has been utilized for construction purposes since ancient times. The tree is also integral to the establishment of truffle orchards, as truffles grow in an ectomycorrhizal association with its roots. The acorns of Quercus ilex are edible and can be used as a food source for free-range pigs reared for ibérico ham production. They can also be boiled and used as a medicinal treatment for wound disinfections.
This oak can be clipped to form a tall hedge and is ideal for coastal windbreaks. Its attractive rounded head and solid evergreen characteristics make it a valuable addition to urban and garden settings. However, it is not tolerant of cold continental winters and thus not suitable for areas with severe frost.
Some notable Holm Oaks include the TROBI Champion in Gloucestershire, which measured 27 1⁄4 ft (8.3 m) in circumference at 1.2 m height in 1993. Another remarkable tree can be found at Courtown House in Wexford, Ireland, which was reportedly planted in 1648 and now stands at 20 meters (65 feet) tall with a spread of 43 meters (141 feet).
In conclusion, Quercus ilex, the Holm Oak or Holly Oak, is an impressive evergreen oak native to the Mediterranean region. Its large size, dense foliage, and unique appearance make it a popular choice for landscaping and garden settings.