Oak Tree

Oak Tree

Quercus species

The oak was sacred to many people, including the ancient Greeks, the Norse and the Celts. It was often associated with the gods of thunder as oak was often split by lightning. This is probably because oaks are often the tallest tree in any area. More recently oak was the sacred wood burnt by the druids for their mid-summer sacrifice. In fact the word ‘druid’ means ‘oak man’ In modern history, tradition has it that Charles II hid in an oak tree at Boscobel when pursued by the Roundheads. Since then, children wear oak leaves on May 29th to commemorate Royal Oak Day (now known as Oak Apple Day). Oak is the common name for many acorn-producing trees and shrubs that are members of the beech, or Fagaceae, family. Geographic Society and is part of the National Historic Landmark district of Hampton University. Although it is rarely reached, the symbol of an 80th wedding anniversary is oak. In Britain, an oak tree image is engraved in a six pence coin. It is one of the oldest Britain’s coins. Oak branches are displayed on some German coins, both of the former Deutsche Mark and the current Euro currency. The Royal Oak is the third most common pub name in Britain. Oak trees are classified as members of the genus Quercus, a Latin word said to be derived from a Celtic word meaning "fine tree." They thrive across the Northern Hemisphere in China, Japan, Europe, the British Isles, and in all of the continental United States except for Alaska. More than half of the 600 species are native to North America. About 60 varieties grow north of Mexico. In the forests of northern areas that have short summer growing seasons and long winters, such as Canada, northern Europe, and Siberia, varieties of oak are very scarce.

Also called Common Oak or English Oak, the Oak is the largest of our native broad-leaved trees, regarded as “the King of the forest”, Oaks are sturdy and tall with domed crowns. The broad rounded canopy has wide spreading thick lower branches. There are two native Oaks in Wyre, the other being the Sessile Oak (Quercus petraea). Both have the different characteristics of leaves and acorns.

Oaks then produce a new flush of leaves, especially on young trees, and this phenomenon is called lammas growth, because it occurs around the time of Lammas, the Celtic festival of first fruits, on 1st August. In autumn, the leaves turn various shades of yellow and brown, as chlorophyll is withdrawn from them and carotenoid pigments become visible instead. In some areas, the leaves are shed at the end of October, but in milder areas a few leaves will stay on the trees until December.

Oak trees can be found around the world across a large variety of terrestrial biomes. There are more than 80 species of oak in North America. Oaks can grow over 40m high and over 3m in diameter. Often 1000 years old. White and red oaks need slightly acidic, well drained soil to access their nutrients. Subterranean mycorrhizal fungi found along the roots of many plants, help oaks to take necessary nutrients from the soil. Oaks need full sun. The leaves have large deep lobes and smooth edges. There are two tiny lobes where the leaf joins the stalk. They are dark green, turning orangy-brown in autumn. The leaf stalk is short. The greyish bark has very knobbly ridges and deep fissures.

Oak timber is strong, elastic and durable. The heartwood resists penetration by liquids, making it ideal for posts in contact with the ground. The timber is best once the tree has reached about 150-200 years old. It has conspicuous growth rings which give a characteristic silver grain when quarter-cut or split. It is ideal for making furniture, barrels, railroad ties, and in the past, ships.

The tannin in oak bark is used in leather preparation. Cork is made from the bark of some species that grow only in Spain and Portugal. Recent advances in molecular genetics have shown that DNA from samples of oak can be isolated and analyzed. This type of analysis has a variety of potential applications in archaeology and forensic investigations. Oak used to make wine barrels has been found to increase the antioxidant activity of wines aged in the barrels as well as adding a distinctive aroma to the wine.

One teaspoonful of pulverized oak bark powder can be added to 1 cup of water, boiled, and then simmered at a reduced heat for 15 minutes to make an oak bark tea. This tea can be taken internally as an intestinal astringent up to three times per day. Oak bark is also available in both an extract and a tincture. For rinses, compresses, and gargles, 20 g of pulverized bark should be dissolved in 1 qt (1 L) of water, and prepared in the same manner as the tea. Oak bark is also available as snuff, tablets, and capsules.

Oak bark should not be used externally over large areas of skin damage or used as a full bath. Oak bark for gargles, enemas, or douches should not be used for more than two weeks before consulting a doctor. A doctor should also be consulted for any episode of diarrhea that lasts longer than three days despite treatment with oak bark. No side effects have been reported when oak preparations are used at recommended dosage levels. Patients occasionally experience mild stomach upset or constipation if the dosage is exceeded. Oak bark preparations are believed to inhibit or reduce the absorption of such alkaline drugs as antacids. In addition, oak bark has been found to reduce the effectiveness of codeine and atropine.

Oaks are deciduous species and most drop their leaves each fall. The age of first reproduction varies with geographic and local position, tree density, and life span. In order to reproduce, oaks are wind pollinated. Growth of male flowers begins in the spring, they develop in the summer, and produce pollen the following spring. Female flowers develop in late winter or early spring. Acorns, the result of pollination, mature 3 months after fertilization. Birds and mammals are the major predators of acorns, but they also move acorns around.

Acorn survival to adulthood depends upon their movement. Small mammals that store acorns can disperse acorns short distances (mice) or greater distances (chipmunks and squirrels). Larger animals and birds tend to destroy the acorns. Some birds that utilize acorns only eat them and others store them above ground (leaving them to be consumed by other predators). Only birds such as jays, who store acorns below ground and “space hoard” – spreading their stash across space, actually facilitate the dispersal of acorns.

Acorns are a source of food for rodents, deer, birds, and other wildlife. Birds feed on leaf buds. Deer also feed on leaves and twigs while the tree is young. Invertebrates feed on the leaves or on other invertebrates. In particular, adult moths lay eggs on oak leaves. When the caterpillars hatch, they consume the leaves. Some insects cause the tree to produce “galls” outgrowths of the bark, in which the larvae will develop. Other insects, such as beetles, weevils, and spiders can also be found. Fungus and lichens can also grow on oaks.

350 different species of insect are supported by Oak. A single oak tree may have over 30 different lichen species on its bark. Huge numbers of creatures seek food and shelter in crevices of the bark, in the canopy of fresh leaves, hollow trunks of old trees, leaf litter and branches of dead wood and rotting wood on the forest floor.

Red Oak

Each species of red oak behaves more or less the same, taking 2 years to mature their acorns

- Key identification: Leaves have pointed lobes.

- Red oak species in Southern Ontario include Pin oaks, Black oaks, and Northern Red Oaks.

- Trees produce acorns every 3 to 5 years

- Forecast in the last week of June to the first week of July.

• Look at the tips of branches at the ‘drip line’ of the tree (the edge of the crown). Look for green acorns that are starting to come out of the caps. Binoculars will be helpful. Since red oaks take two years to grow their acorns, you may also see smaller bumps that look like scaly balls. These are the beginnings of next year’s acorns, most closely resembling the cap of the acorn. They will be round with no acorn visible.

White Oak

White oak species produce mature acorns in one year.

-Key identification: Leaves have round lobes

-White oak species in Southern Ontario include Bur oak, Swamp oak, and English oak (introduced).

-Trees produce acorns every 4 to 10 years.

-Forecast in the last week of July.

• Look for acorns at the tips of branches at the drip line. The acorns will be very small and green. Binoculars will be helpful.

Sessile Oak - Quercus petraea

Regarded as “the King of the forest,” Sessile Oaks have straighter branches than the Pedunculate Oak, radiating from a more upright trunk. Sessile and Pedunculate Oaks often hybridise and their ranges overlap. In Wyre you may find leaves with rounded lobes at the base with a long stalk, for example. Oaks can grow over 40m high and over 3m in diameter. Oaks often reach an age of 300 years old.

British people have always loved the Oak. Its great size, low branches and hollows in the trunk mean it was used as a natural tree house, hiding place and social centre. Robin Hood was said to have lived in the Major Oak in Sherwood Forest. Kings and Queens have hosted many a social event around a big old Oak. Oak trees were often landmarks and are still found in many place names such as Sevenoaks in Kent, England. The Gaelic word for Oak is “dairoch” and is seen place names in Scotland such as “Craigendairoch” or “Clasindairoch”. The Welsh word “der” can be seen in place names like Derwen and Deri. In Irish “doire” means oakwood.

The Sessile Oak is widespread, particularly in North and West Britain, including the Wyre Forest. The acorn is the ripened fruit or seed of the tree. It looks like an egg in a cup. Unlike the Pedunculate oak, the acorn of a Sessile oak has almost no stalk. The wavy dark green lobed leaves are very distinctive with their long (1-2cm) yellow stalks. The leaf bases do not have rounded lobes at the base, but are wedge shaped. The Greyish bark has very fine vertical cracks and ridges forming shapes called “plates”.

Oak - associated fungi and lichens

Chlorociboria aeuruginacens - A saprophytic fungus common in The Wyre on dead oak branches.

efsteak fungus - Fistulina hepatica - This parasitic fungus attacks Oak and can give a deep brown colour to the timber, enhancing its market value.

Bulgaria inquinans - A saprophytic fungus common in The Wyre on dead oak branches

Bryophytes - are the group of non-flowering plants which include mosses and liverworts, and 65 species grow on the trunks and branches of oaks.

Lichens - A remarkable diversity of lichens, totalling over 300 species, have been recorded growing on oaks.

Oak apples and other galls - grow around the eggs of insects laid in the buds. Over 40 species, including midges, mites and wasps, are responsible for stimulating the oak to produce these unusual growth forms on its leaves or twigs, within which the larva of the insect lives and feeds.

Great Oak Beauty Moth - Hypomecis roboraria - A large but well camouflaged moth whose caterpillars resemble a twig when at rest, and feed on oak leaves.

Purple Hairstreak - The purple hairstreak (Neozephyrus quercus) is the only butterfly whose larvae feed exclusively on oak leaves.

Wood Ant - The ants climb to the top of the tree to find the aphids which they then “milk” by stroking them until they ooze sweet, sticky honeydew.

There is a lot of competition for the acorns of the Oak tree. Here are the main suspects to look out for.

Grey Squirrel - They peel the acorns first then bury them to store for winter food.