There are several hundred varieties of oak trees, which are members of the genus Quercus. These majestic trees are primarily native to the northern hemisphere and include both deciduous and evergreen species.
Varieties of Oak Trees
While there are hundreds of varieties, some are more commonly grown in gardens and parks than others. They present a wide range of colors and sizes, from giants that soar to nearly 200 feet tall, to more diminutive, shrub-sized varieties.
Chestnut Oak (Quercus montana), is a tall tree with a maximum height of over 150 feet, with grey flaky bark and chestnut-like leaves, shiny on the upper surface and greyish beneath. It grows very well in drier soils.
In his wonderful book A Sanctuary of Trees, Gene Logsdon refers to white oaks (Quercus alba) as "the overarching monarchs" of the forest, and with good reason. These behemoths can grow to 150 feet tall. They have deeply-lobed leaves and gray bark that scales off in plate-like chunks. It's very cold hardy, native to Canada and the northern United States.
Turkey Oak (Quercus cerris) has deep green and finely cut foliage. It is also much more rapid in growth and will flourish in light and varied soils. It retains its foliage longer than most other trees, and some of its varieties are almost evergreen.
- The chief of these is the Lucombe Oak, a tree of graceful growth, which rapidly ascends into a tall cone of foliage and retains its leaves through mild winters.
- The Fulham Oak is a similar tree of hybrid origin. It is also partially evergreen, and differs from the Lucombe Oak chiefly in its habit of growth being more spreading.
- The variety known as Q. austriaca sempervirens is a form of the Turkey Oak sub-evergreen in character and of medium growth, and useful for small gardens.
These varieties rarely equal the wild tree in beauty or character, and have the disadvantage of being increased by grafting, which bars them from ever attaining the stature and dignity of the wild tree.
The Scarlet Oak (Quercus coccinea) grows to 160 feet high in its native habitats. Native to North America, it's a beautiful tree at all seasons, but particularly so in the autumn, when the rich scarlet and crimson hues of its fall foliage are very handsome.
Hungarian Oak (Quercus frainetto) is a noble tree in its own country, and one of the quickest growing oaks in cultivation. It has much larger leaves than the common oak, and they are cut in much the same way. It is a good oak to plant as a tree of the future, as it is very hardy and grows well in almost all kinds of soil.
Bur Oak (Quercus macrocarpa) is a large forest tree with a maximum height of 160 feet and a trunk as much as 8 feet in diameter. It has rather large, thin, deeply incised, but blunt-lobed, leaves, shiny on the upper side and whitish below. The timber is good and tough. It's a native of rich soils from Nova Scotia to Manitoba and also southwards.
Post Oak (Quercus minor) is a tall tree, sometimes growing up to 100 feet high, with rough gray bark and deeply incised but blunt pointed leaves. The wood is very hard and durable. Post oaks are native to North America.
Water Oak (Quercus nigra) isn't as tall as other oaks, growing to around 80 feet tall. There is a variety of it in cultivation named nobilis, which has leaves nine inches or more in length of a rich green. It makes a handsome landscape tree and especially appreciates wet, slightly swampy conditions. Water oaks are native to the United States, generally along coastal areas in the east, west, and south.
Pin Oak (Quercus palustris) is a forest tree with a maximum height of 120 feet. It is one of the quickest growing oaks, and its chief beauty is the tender green, almost yellow, of the unfolding foliage in May and rich autumn tints. It grows really well in marshy places, as it grows naturally in such ground. Pin oaks are native to North America.
British Oak (Quercus robur) is one of the most beloved British trees, growing in woods, parks, by rivers, and in pasture land, as well as in home gardens. It can grow up to 100 feet tall, and is valued as both a timber and landscape tree. Its fall foliage is yellowish, fading to brown.
Willow Oak (Quercus phellos) is a forest tree that grows to around 80 feet high, and unlike the other oaks in that its foliage is more like that of a willow, narrow and long and whitish beneath, giving the tree a silvery appearance on a windy day. It is not a common tree, though it is native to North America. It grows rapidly in well-drained light soils, especially in a gravelly subsoil, and grows much more slowly in cold, wet soil.
Swamp White Oak
Swamp White Oak (Quercus bicolor) has flaky green bark and grows to over 100 feet tall. It has slightly lobed leaves and its acorns form on rather long stalks. Swamp white oak is a native of moist and swampy soils in Canada and west to Michigan.
Rock Chestnut Oak
Rock Chestnut Oak (Quercus prinus) sometimes attains a height of 100 feet. Its leaves are somewhat chestnut-like, and the tree bears an edible acorn. It's native to the eastern U.S. and Canada and grows best in dry soil.
Northern Red Oak
The northern red oak (Quercus rubra) is an enormous forest tree with a maximum height of nearly 150 feet, making it one of the most majestic American trees. Aside from its awe-inspiring size, the champion oak also produces deep, rich fall color. It grows best in well-drained, deep soil, and is much more rapid in growth on moist than on dry soils. It's native to Canada and eastern United States.
Sessile Oak (Quercus petraea) is another species of British oak, though it has a straighter and more cylindrical stem and form of tree even than British Oak (described above), and is of a deeper green, has denser foliage, and provides deeper shade. The leaves are also a little longer than those of the British oak, and sometimes, in mild winters, they remain on the tree until the others come. It grows best in dry, sandy soil.
Black Oak (Quercus velutina) is a tall tree, growing up to a massive 150 feet. The outer bark is a very dark brown, and it has deeply cut leaves with sharp points. It is native to the northern United States and into Canada.
Japanese Evergreen Oak
The Japanese evergreen oak, Quercus acuta is a native of Japan, south Korea, Taiwan, and parts of China. It has dark, leathery leaves that grow to two and a half to five inches long. The foliage is unlike what you usually expect from an oak tree; the glossy leaves are oval, narrowing to a tip, and they're yellow underneath. It's a fairly rare tree outside of its native habitat.
Coast Live Oak
The coast live oak (Quercus agrifolia) is a large tree with a fairly thick trunk, often 8 to 12 feet in circumference. Its branches can spread up to 120 feet, making this an excellent shade tree if you have the room for it. It has deep green leaves and produces reddish-brown acorns. Coast live oaks are native to California and prefer well-drained soil.
Canyon Live Oak
The canyon live oak (Quercus chrysolepis) is another native of the western United states, growing along the coast ranges and along the western slopes of the Sierra Nevada. It forms a trunk three to five feet in diameter, or, at higher elevations, grows in more of a shrub-like form. It has pretty spiny-toothed dark green leaves, somewhat golden on the under surface, and is evergreen in its native habitat.
Kermes oaks (Quercus coccifera) are dense shrubs with small, spiny, dark green leaves and very small acorns, often hardly larger than a pea. Kermes oaks are native to the Mediterannean and grow to around six to seven feet tall. It does best in warm climates and loose, sandy, or even gravelly soil.
The tanbark oak (Notholithiocarpus densiflorus) was only recently reclassified, given a new genus, when it was formerly classified as a Quercus. Native to the mountains of California, it grows to 50 to 60 feet high, though in some situations, it's often seen growing more like a shrub.
The holly oak (Quercus ilex) is an evergreen oak that most closely resembles an olive tree in terms of its shape and growth habit. It reaches about 60 to 70 feet tall and produces a dense canopy of oval-shaped leaves. It's native to the Meditteranean, growing mostly in Greece and certain areas of the Iberian peninsula.
Cork Oak (Quercus suber) is a medium-sized evergreen oak that's often used for--you guessed it!--making corks for wine bottles, cork flooring, and corkboard. Cork oaks are native to northwest Africa and southwest Europe. It produces leathery, lightly serrated oval leaves and clusters of two to eight acorns. It's hardy in Zones 8 through 10.
Southern Live Oak
The southern live Oak (Quercus virgiana) is native to the southeastern United States. It has thick, dark, furrowed bark and shiny, dark green, nearly lanceolate leaves. These trees grow to about 40 to 80 feet tall, and are hardy in Zones 8 through 10.
Description of Quercus: The Mighty Oak
Culturally, the oak is a symbol of strength and endurance. It is the national tree of Germany, the United Kingdom, and the United States. Oaks were considered sacred by the Celts, and the name of their priests, druid, comes from the words for oak and for knowledge.
Oak trees grow slowly to a mature height of 100 feet with a spread of 50 to 80 feet. They are deciduous broadleaf trees. Most oak leaves, though not all, have lobed margins that turn yellow or brown in the autumn. The edible fruit is a nut, generally referred to as an acorn.
The oak typically lives from 200 to 600 years. Oaks are used as food plants by the larvae of many Lepidoptera species.
How to Grow Oak Trees
Oaks prefer deep, rich, slightly acidic loam with plenty of organic matter. They are, however, quite tolerant of other soils. Their leaves are slightly acidic and, if allowed to compost where they fall, will gradually change the soil to the tree's preferred pH level.
Oaks grow best in full sun to light shade. Many oaks are tolerant of urban pollution and soil salt, so they are often grown as street trees. Many are hardy to Zone 4, though those that are native to Meditteranean or southern climates are usually hardy only to Zones 7 or 8.
Most oak species prefer evenly moist soil but are tolerant of wet and dry conditions once they are established.
Oaks need little maintenance. Dead or damaged wood can be removed at any time. Other pruning should be done in late winter or early spring.
Trees should be transplanted while still small. Oaks should be transplanted in the spring for best results. Water the transplanted saplings regularly for the first two seasons until the root system is established.
Oaks seed themselves readily if acorns are left on the ground.
Problems to Watch For
Most oaks are not troubled by pests or diseases. The most common diseases are a water mold, sudden oak death (Phytophthora ramorum), and a fungus, oak wilt. Older trees may suffer from root rot.
Uses for Oak Trees
Most oaks are large trees! They are usually planted as specimen and/or shade trees. The leaves of many species turn a brilliant gold in autumn.
Oaks are hardwood trees and are valuable commercially for furniture and flooring, especially the various red oak and white oak species. The bark of the cork oak is used to produce stopper for wine and olive bottles. Several species are valued for making barrels to age wine and spirits; the oak wood contributes to the taste of the final product.
Traditionally, white oak bark was dried and used in medical preparations. Oak bark is rich in tannin, and is still used in tanning leather. Acorns can be ground for flour, roasted for acorn coffee, or used as a food source for some livestock.
Beautify Your Landscape With Oak
The majestic beauty of an oak is truly something to marvel at. If you don't have one in your landscape already, check with your local garden store to find a variety that suits the climate in your region.