Nature Bulletin No. 316 Forest Preserve District of Cook County
October 11, 1952 William N. Erickson, President
Roberts Mann David H. Thompson
Supt. of Conservation Senior Naturalist
The oak has long been a symbol of rugged strength and nobility. Of all our hardwood trees, the oaks are unsurpassed in grandeur, size, length of life, numbers and commercial value. There are more than 80 kinds in the United States, including the evergreen live oaks, and probably 20 of them are found in Illinois, but some are difficult to identify and tell one from the other. Moreover, the same common name may be used for two different kinds, depending upon the locality.
There are two general classes: the White Oak group, and the Red Oak or Black Oak group. In the first, the ends of the leaves and their lobes are rounded without any spines or bristles at the tips. Their acorns, which are relatively sweet and edible, mature and fall off the same year they are formed, so that there are none on the branch in winter. In the Red Oak or Black Oak group, the leaves and their lobes, if any, have bristly hairs or spines at the tips. The acorns, which are bitter with tannin, do not mature and fall off until the second year, so that small ones may be seen on the branches in winter.
Unfortunately for us ordinary folks, there is commonly a considerable variation in the size and shape of the leaves on any given kind of oak, especially on young seedlings, on sprouts from stumps, and also on vigorous new shoots on older trees. Furthermore, some oaks cross-pollinate and the leaves of such hybrids can be a puzzle. The expert forester or botanist may identify an oak by its leaves and other characteristics but he depends chiefly on the size and shape of its acorns, and the size shape and texture of the cup that holds the acorn.
In the Red Oak group are the species commonly and best known as northern red, southern red, pin, scarlet, black, Hill's black, scrub, blackjack, willow, shingle and laurel. They and their relatives make up more than half of the total stand of oaks in the United States and are all usually marked as “red oak”.
The Northern Red Oaks are the most important, fastest growing and attain the greatest size. They extend from Nova Scotia to central Minnesota and south to Arkansas, northern Louisiana, Tennessee and northern Georgia. In Illinois we have only the larger of the two varieties. Ordinarily, the older trees are from two to four feet in diameter and 70 to 90 feet in height, but in the Ohio valley and the Appalachian regions some have become 150 feet tall and six feet in diameter.
Red Oak lumber although not equal to white oak, is extensively used for the same purposes: such as general construction, flooring, interior finish, and furniture. It is not durable in the soil, however, and red oak posts or railroad ties should be pressure treated with a preservative.
The leaves, smooth and dark green above and paler below, have from five to eleven bristle-tipped lobes. In autumn they turn deep red or orange, then brown and on some trees may hang on until midwinter. The acorn is usually an inch or more in length and is held in a shallow saucer-like cup which is covered with closely fitting scales. The acorns are very nutritious. They are important food for squirrels, foxes, deer and many other kinds of wildlife. Hogs in wooded pastures, gobble them greedily and grow fat. The Potawatomi and other native people, who knew how to remove the tannin, ground them into a meal for food.
….It takes a mighty red oak to make a Potawatomi pancake.
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