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. The "live oaks" (oaks with evergreen leaves) are not a distinct group, instead with their members scattered among the sections below.
More on oaks: An Introduction to Oak Trees
The Common North American Oak Species
- 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
Dormant Oak Identification:
Has 5-sided pith; has variable bark so not very helpful; has clustered buds at tip of twig; has persistent leaves on live and water oak; has slightly raised, semi-circular leaf scars; has numerous bundle scars; has acorns persistent on twigs or dropped under the tree.
Leaves: alternate, variable in shape, short stalked.
Bark: gray and scaly or blackish and furrowed.
Twigs: slender with star-shaped pith.
Fruit: acorns.
