How to Recognize Oak Trees

Watch how an oak tree changes shape as it grows, from a thin tree with climbing limbs and drooping twigs to a powerful, strong tree topped with what Glenn Keator, botanist and author of "The Life of an Oak: An Intimate Portrait," describes as a "cauliflower-like crown and a clean, unfettered bole." Most of the oak tree consists of bark and wood.

Notice how the young oak tree leaves start out toward the end of spring in a coral pink color, eventually changing from gold to green. All oak leaves have a thin leafstalk, called the petiole, that attaches to a leaf blade. The oak leaf blade varies in shape. For instance, a leaf can look like a wide oval with a pointed tip or a slender spear shape. In the fall, oak leaves change to gold, brown and then drop.

Inspect an oak twig from the bottom to the top and you will find it has five leaves attached with each leaf at a different level, so you have five leaves making two spirals around each twig. Each leaf sitting on the twig at a different angle allows the leaves to grow freely without getting in the way of other leaves.

Look at the end of the oak twigs if you see hard round-looking balls there. Gall wasp larvae live in these balls called oak apples where they lay eggs in the oak tree's bark.

Examine the oak flowers taking note how the female flowers have spiky buds while the male flowers have dangling catkins, long thin flowers without petals. Look closely at the female flowers and you may see a green, unripe acorn growing. By harvest time in the middle of the fall, the acorns will be brown.