Oaks - Evolution, Biology And Ecology, Diseases, Distribution, Historic Importance, Acorns, Wood, Ecological Significance - Economic importance
found flowers genus family
Oaks (Quercus spp.), members of the Beech family (Fagacea), are trees and shrubs having simple, alternate leaves found throughout the world. Characterized by their strong, complex wood, wind-pollinated flowers, fruits called acorns, and their ability to live for centuries, oaks have played an important role in temperate landscapes. Of the 500 species in the genus Quercus, approximately 90 are found in the United States and Canada, with another 112 species in Mexico. Another member of the Beech family that is closely related to the oaks is the tanoak (L. densiflorus), which is found in California and is the only representative of this Asian genus found in North America. It has flowers similar to the chinkapin (Castanopsis) and bears acorns like the oaks, thus making it a possible evolutionary link between the two genera.
Because they are widespread and generally large, oaks have been used in numerous ways. The leaves, flowers, and bark were used by indigenous peoples in both Europe and North America for making medicinal drinks used to cure fevers, stop vomiting, and control diarrhea. Tannins extracted from the bark were used both for dying and tanning hides. The chestnut oak (Q. prinus) was logged to virtual extinction due to the high quality tannin it provided for the tanning industry.
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The Quercus genus is quite old, being one of the early angiosperms of the Miocene epoch (26-12 million years ago). Over time, oaks have divided into two main lineages, with an intermediate subgenus for less genetically distinct species. The red oaks (Erythrobalanus) are characterized by pointed leaves with bristles or spines that can be either lobed or unlobed. The acorns have a hairy inner shell …
Found in a wide variety of habitats, oaks prefer loamy, well drained soils. The roots are quite extensive, reaching out at least three times the height of the tree and down as deep as 15-40 ft (4.6-12.2 m), depending on site conditions. There are both evergreen and deciduous species. Each leaf of the evergreen oaks falls after one to two years, but there is no synchronous leaf loss. New leaves for…
Because of their widespread distribution, oaks play an significant ecological role in many forest communities. Of the 90 forest-type covers described in the United States and Canada, oaks are an important element in 64. and include both evergreen and deciduous species. Some of the more important species in North America include the northern red oak (Q. rubra), the black oak (Q. velutina), and the …
The name Quercus comes from the Celtic, quer meaning "fine," and cuez meaning "tree." Historically, the Celtic religion as well as that of other cultures venerated old oak trees, using them as a focus for spiritual rituals. The Druids believed the oak to be a sacred tree, the symbol of their religion, and potent source of wisdom. The ancient Greeks believed the rustling…
The structural characteristics of the wood make oak one of the most versatile hardwoods, valued by many industries. The strength of oak wood is a result of the inner structure of vessels and fibers. The ring porous nature of the woody tissue results from uneven vessel growth. During the spring and summer, large vessels and fibers grow, followed by smaller vessels as the season progresses. In decid…
In addition to ecological and aesthetic landscape value, another important role of oaks is in maintaining watershed integrity. The sometimes deep, always extensive root system of oaks stabilizes slopes, limits erosion, and allows groundwater recharge. The wide canopies dissipate the rainfall and prevent surface erosion, while allowing slow saturation into the soil. The ability of oaks and other tr…
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