Video:North American Oaks

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Transcript:North American Oaks

The term "oak" can be used as part of the common name of any of about 400 species of oak trees and shrubs in the genus Quercus. The genus quercus is native to the northern hemisphere, and includes deciduous and evergreen species extending from cold latitudes to tropical Asia and the Americas.

Oak Tree Characteristics

Oaks have spirally arranged leaves, with a lobed margin in many species; some have serrated leaves or entire leaves with a smooth margin. The flowers are catkins, produced in spring. The fruit is a nut called an acorn, borne in a cup-like structure known as a cupule; each acorn contains one seed (rarely two or three) and takes 6-18 months to mature, depending on species.

"Live" Oak Trees

The "live oaks" (or oaks with evergreen leaves) are not a distinct group, instead with their members scattered among different sections. Among these are:

• Black oak
• Bur oak
• Cherrybark oak
• Laurel oak
• Live oak
• Oregon white oak
• Overcup oak
• Post oak
• Pin oak
• Northern red oak
• Scarlet oak
• Shumard oak
• Southern red oak
• Swamp chestnut oak
• Water oak
• White oak
• Willow oak

Oak trees have a 5-sided pith, with variable bark. They have clustered buds at the tips of twigs. They have slightly raised, semi-circular leaf scars and have numerous bundle scars. Acorns are persistent on twigs or dropped under the tree. Oak leaves are alternate, variable in shape and short stalked. Twigs are slender with star shaped pith.

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