It might be a surprise to discover that many of the hundreds of oaks found worldwide are not deciduous but evergreen. Among all these evergreen species, only one, the holm oak, which can be found in the Eastern Mediterranean, is also common in Britain.
Holm Oak is an evergreen tree that grows up to 20m. The female flower is an acorn, while the male flower is a catkin. Holm oak offer pollen for bees and other insects and many birds may be found nesting in its canopy.
If you want to know more about this fantastic tree, please read on.
The holm oak is not native to the British Isles. It comes from the Mediterranean countries and was introduced here from the Cape Finisterre region of Spain at the end of the 16th century. Most likely, it was brought over here by merchants and sea captains, either as seedlings or as acorns.
The tree proved successful in Britain, especially in the milder climate of southwest England, where it has become naturalized. In the rest of the country, it is found primarily in town parks and gardens. It is particularly useful as a source of shelter in coastal areas, where its thick leathery leaves can resist the drying effects of sea winds.
The name ‘holm oak’ comes from the old word for holly, ‘holnf, because the leaves of the two trees are quite similar. However, this tree has several other names, including the evergreen oak, the live oak, and the holly oak. Its botanical name, Quercus ilex, refers to its holly-like leaves, Quercus meaning oak, and ilex being a generic name for holly.
The leaves may have smooth margins or may be toothed, resembling holly leaves. Frequently the leaves are also curved downwards slightly.
The color is less variable than the shape, being dark green above and buff-grey below. The undersides are covered with tiny white hairs, like the leaf stalks and the young twigs.
The tough leathery leaf surface makes the holm oak unusually resistant to pollution because any dirt falling on it is easily washed away by rain. The leaves have a felted underside which also helps to keep out pollution by preventing the stomata from becoming clogged up.
Stomata are pores on the leaf surface that allow gases to be exchanged between the leaf and the atmosphere. This is the main reason the holm oak grows well around towns.
Usually, the holm oak sheds its previous year’s growth of leaves in May and June, but severe frost may cause the leaves to turn brown by the spring. In this case, the leaves are shed early, but the tree quickly becomes green again as the dormant buds in the leaf axils are stimulated to grow.
Flowers and fruit
The male and female flowers are borne separately, although from the same tree. Male flowers are catkins 4-7cm (Il-3in) long. They are hard to see at first but become more noticeable as their yellow pollen ripens in mid-June.
The female flowers are solitary and inconspicuous. After pollination by the wind, they develop an acorn cup at their base, in which the fruit slowly forms.
The fruit of the holm oak is an acorn. Its acorn is smaller than that of most deciduous oaks. When young, the acorn is green, turning reddish-brown when fully mature. The cup is stalked and scaly, bearing silvery-grey, closely matted hairs.
In warmer climates, the acorns germinate quickly where they fall, but the seed is not always viable in colder climates.
The holm oak was once used for making carts and carriages wheels and constructing a wide range of agricultural implements. Using wood for wheels may be a tradition dating back to the Romans.
They found it particularly suitable for this purpose because of its hardness, durability, and weight. Today, holm oak timber is not much used around the Mediterranean, though in Algeria, it is still used in carriage building and all forms of joinery.
In Britain, the timber has never been used much except as a fuel source. This is probably because common oak timber is easier to obtain. However, holm oak wood is durable for outdoor purposes such as gateposts and stakes because it contains tannic acid, which preserves the wood.
Superstitions and Folklore
Many trees have folklore and superstitions attached to them, and the holm oak is no exception. The ancient Greeks used the leaves as oracles during their ritual ceremonies. They regarded them as infallible.
Crowns were made from holm oak leaves and used to honor prominent citizens, and the acorns were regarded as symbols of fertility, a belief shared with other cultures. Greek women used to wear imitation acorns made of gold in the hope that they would make them fertile. They used to make these golden acorns into pendants and necklaces.