Quercus - Oak Tree
DESCRIPTION: This is a large group of evergreen and deciduous trees and shrubs that are found wild throughout Europe, Asia, northern Africa, and North and South America. Some require tropical or sub-tropical conditions to survive, while the majority are hardy in the North. The Oaks are varied in their appearance; it is hard to believe that some kinds can be classified with the same species. They do, however, have one characteristic in common, which is the fact that their seeds are carried in little caps. Acorns vary considerably with the different kinds of Oak trees. Some have stalked or stalkless caps; in some, the caps only enclose the base of the acorn, while in some, only the tip peaks out. Some caps are rough because they're made of irregular scales; others are smooth because their scales are even and smooth. Some acorns mature six months after the flowers appear and some take as long as 18 months to ripen. Male and female flowers appear on the same tree. The male flowers are borne in noticeable thin, catkins and the inconspicuous female flowers are produced two or more, or sometimes singly on a short stalk. As mentioned above, some Oaks lose their leaves and some donít and some need warmer climates than others. A few will be described for each of these characteristics.
Evergreen Oaks - Evergreen Oaks include many American and exotic trees. Q. virginiana, the Live Oak, is one of the most beautiful of American Oaks. It sometimes grows up to 70 feet, but usually stays around 50 feet. It is a wide spreading tree with dark green, shiny leaves that are whitish below. This tree grows naturally from Virginia to Florida and Mexico. It is a favorite in the South as a shade and street tree because of its beauty, its rapid growth, and because it is fairly easy to transplant. It is also valued for its timber. Q. Suber, the Cork Oak, has corky bark. It is a native of southwestern Europe and northern Africa. It is commonly planted in California. This is the tree from which commercial cork is obtained.
North American leaf- losing Oaks - North American leaf-losing Oaks are divided into two groups. One is the White Oak group, in which the leaves and lobes of the leaves don't end in bristles, and the acorns ripen during the first year; the other is the Black Oak group, which produces acorns that ripen the second year and the lobes of the leaves are usually tipped with bristles. Q. alba, the White Oak, is a native from Maine to Florida and Texas. This tree is one of the largest of the trees. On average, they will grow from 60 to 80 feet high, but they frequently grow much larger. The leaves are from 5 to 9 inches in length and about half that in width. They have from 5 to 9 (usually 7) rounded lobes. They are smooth, bright green above and whitish beneath. The acorns have short stalks. They are egg-shaped, light brown and shiny, about ĺ-inch in length. Only about a quarter of their length is covered by the cap. In the autumn, the foliage turns a beautiful purplish-red color. Q. coccinea, the Scarlet Oak, is a member of the Black Oak group (the former, Q. alba, was a member of the White Oak group). This is one of the most beautiful of the American Oaks. It grows up to 80 feet high with a diameter of 1 or 2 feet. When young, it has a somewhat pyramidal crown, but as it gets older it develops a broad, round head. The leaves are from 3 to 6 inches long. There are from 5 to 9 long, narrow lobes, which are tipped with bristles and sparingly toothed. The tops of the leaves are dark green and glossy and below they are paler and fairly smooth. The nuts are light reddish-brown with a brown cap, which covers about half of the nut. In the fall, the leaves turn a gorgeous scarlet.
Exotic leaf-losing Oaks - Q. canariensis is an exotic leaf-losing Oak from Algeria and Portugal, where it can attain heights up to 100 feet. The leaves on the young trees are from 5 to 7 inches long and half as wide. They usually stay on the tree until very late in the season. This kind can only be grown in mild climates.
The wood of the Oaks has been for years important for many things. It was once used extensively for the roof lumber of public buildings, churches, cathedrals, etc. . . It was also used for paneling, doors, and furniture; there is still quite a demand for Oak for this kind of work. At one time, it was used for building ships. Oak bark is very high in tannin. The bark of the Cork Oak, Q. Suber, is the cork of commerce. Q. Suber is a native of Spain, Portugal, Algeria and other parts of north Africa. Cork stripping is a very important trade in these countries. The first bark taken from a tree is called virgin cork and is of lesser value. This cork is used for horticultural purposes and, when ground, is in demand for the manufacture of cork mats, linoleum, etc. After removal from the tree, the cork is submitted to pressure and is marketed as flat sheets. Waste cork from the manufacture of bottle corks is ground and used as virgin cork.
POTTING: Most Oaks can live in a variety of soils, but the best kind is deep, loamy soil that is moist but not waterlogged. The Scrub Oaks will grow in poor, dry soil. When Oaks are to be planted where soil is poor, larger holes should be dug and the bottom should be spaded deeply. Generous quantities of manure, compost or other decayed organic matter, and rich, loamy soil should be placed into the hole at planting time. This is very important, especially if they're to be used as street trees. Most Oaks should be planted in their permanent positions as early as possible. This is particularly necessary with the evergreen kinds. While they are still young, they should be transplanted every two or four years to ensure a compact mass of fibrous roots. Any injured roots should be cut back. The leaf-losing kinds may be planted at any time between fall and the beginning of new growth in the spring, as long as the weather is mild and the soil moist. Early autumn and spring are the best transplanting times. The Pin Oak is one kind that transplants well even when fairly large. The evergreen kinds, such as Q. virginiana and Q. Suber, succeed best when moved to permanent spots in early fall or late spring, but before new growth begins. The branches should be pruned to reduce the demand for moisture on the stressed roots. A good soaking should be given when the work is completed. If the leaves happen to fall from the newly transferred evergreens, everything is fine; however, if the leaves die, but do not fall, the branches should be cut back and the stems kept moist. Regular pruning should be started by the time the trees are a year old. The goal is to obtain a clear, central trunk and a shapely head of branches. Side shoots should be removed as necessary. Once your trees have been set in their permanent positions, pruning should be done every other year until they are able to maintain their shape without assistance. Old trees that show signs of deteriorating can be improved by cutting out dead wood, cleaning out and disinfecting cavities, and fertilizing. Trees that have branches with dead ends can be improved by cutting off the wood 9 to 12 inches below where they are dead and protecting the wounds with tree-wound paint. While you are doing this, try to keep the original shape as much as possible. It the ground beneath the trees is very hard, fork it over to let in air and water and give a surface dressing of rich compost and manure.
PROPAGATION: Acorns lose their vitality quickly if allowed to dry. They may be kept for a several months if they are spread on a damp floor or mixed with slightly moist peat moss, leaf mold or sand. When they are being shipped long distances, they must be sent in slightly damp moss, sawdust, peat moss, or powdered charcoal. Acorns should be collected in the fall, stored, and sown in the spring after being rolled in red lead; this discourages mice, birds and other animals from disturbing them. Protect your acorns from birds by covering the bed with a double thickness of wire mesh. If only a few trees are wanted, plant them in containers and place in a frame or greenhouse and make sure the soil is moist. When they are planted outside in a nursery bed, set them an inch or two apart. Sowing the seeds directly where they are to grow would be advantageous because Oaks form long taproots in the first year or two and transplanting often damages that root and causes stunted growth. Seeds of rare kinds should be sown in a frame. Varieties that don't come true from seeds should be increased by grafting. Shoots that are at least two years old should be used as scions and they should be grafted on understocks of closely related kinds. Layers or cuttings aren't used to propagate Oaks. If acorns of rare kinds are wanted that are growing near other Oaks, it is smart to cover the female flowers in muslin bags and hand pollinate as soon as the stigma is receptive, otherwise cross-fertilization will most likely take place.
Evergreen Oaks - American origin - Q. virginiana (Live Oak); Q. chrysolepis (Maul Oak or Canyon Oak); Q. agrifolia (Coast Live Oak); Q. durata (Leather Oak); Q. dumosa (California Scrub Oak); Q. Engelmannii; Q. Wislizenii. Exotic origin - Q. acuta (Japanese Evergreen Oak); Q. coccifera (Kermes Oak); Q. glauca; Q. Ilex (Helm Oak or Holly Oak); Q. myrsinaefolia; Q. phillyraeoides; Q. Suber (Cork Oak).
American Leaf-losing Oaks - White Oak group - Q. alba (White Oak); Q. bicolor (Swamp White Oak); Q. Garryana (Oregon Oak); Q. lobata (Valley Oak); Q. lyrata (Overcup Oak); Q. macrocarpa (Burr Oak or Mossy-Cup Oak); Q. Prinus (Chestnut Oak); Q. prinoides (Chinquapin Oak); Q. Michauxii (Basket Oak, Cow Oak or Swamp Chestnut Oak); Q. stallata (Post Oak). Black group - Q. coccinea (Scarlet Oak); Q. ellipsoidalis (Jack Oak); Q. falcata (Spanish Red Oak); Q. ilicifolia (Scrub Oak); Q. Kelloggii (California Black Oak); Q. laurifolia (Laurel Oak); Q. marilandica (Blackjack Oak); Q. nigra (Water Oak); Q. palustrus (Pin Oak); Q. Phellos (Willow Oak); Q. borealis (Red Oak, Northern Red Oak, or Gray Oak); Q. velutina (Black Oak).
Exotic Leaf-losing Oaks - Q. Robur (English Oak); Q. Robur var. Concordia (Golden-leaved Oak), filicifolia, heterophylla, pendula, purpurascens, atropurpurea, fastigiata, variegata; Q. petraea (Durmast Oak); Q. Cerris (Turkey Oak); Q. castaneifoloia (Caucasian Chestnut-leaves Oak); Q. Frainetto (Italian Oak); Q. canariensis; Q. libani (Lebanon Oak); Q. hispanica; Q. Aegilops (Valonia Oak); Q. dentata; Q. aliena; Q. glandulifera; Q. mongolica.
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