The leaves of Indiana oaks are deciduous; flowers appear in April or May, very small, the staminate on slender pendulous catkins, the pistillate solitary or in clusters in scaly bud-like cups; fruit an acorn which takes one or two years to mature, ripening in September or October. The species that mature their fruit the first year are popularly and commercially classed as "white oaks." Those that mature their fruit the second year are classed as "red, black or bristle-tipped oaks."

The oaks are the largest genus of Indiana trees, and commercially are the most important of all trees of the State. They are the longest lived of all the trees that occur in the State, and while they have numerous insect enemies none of them prove fatal to it, except a certain gall insect.

Note:—In collecting leaf specimens of oaks for identification it should be borne in mind that the foliage is quite variable. The leaves of seedlings, coppice shoots and of vigorous shoots of old trees sometimes vary considerably in size, form and leaf-margins. Also leaves of old trees that grow in the shade usually have the margins more nearly entire than the typical leaves. For example leaves may be found on the lower and interior branches of a pin oak which are not lobed to beyond the middle, which throws them into the red oak group.

Bark gray, (except in No. 5) more or less scaly; mature leaves never with bristle tips; fruit maturing the first year.
Mature leaves smooth beneath[1 Q. alba.]
Mature leaves pubescent beneath.
Primary veins beneath show regular pinnate venation. Some of the primary veins beneath end in a sinus[2 Q. bicolor.]
All primary veins beneath end in teeth of the margin Tips of leaves of fruiting branches sharp-pointed, usually forming an acute angle; fruit sessile or nearly so[3 Q. Muhlenbergii.]
Tips of leaves of fruiting branches rounded or if sharp-pointed, it rarely forms an acute angle; fruit peduncled.
Petioles green and woolly pubescent beneath (rarely almost glabrous); under surface of leaves velvety to the touch; bark gray, scaly, of the white oak type; trees of low ground[4 Q. Michauxii.]
Petioles yellowish and smooth beneath, or rarely somewhat pubescent; under surface of leaves not velvety to the touch; bark dark, and tight, of the red oak type; trees of high ground (in Indiana confined to the "knobstone" area)[5 Q. Prinus.]
Primary veins beneath show irregular venation.
Last year's growth pubescent; acorns generally less than 12 mm. in diameter[6 Q. stellata.]
Last year's growth glabrous or nearly so; acorns more than 12 mm. in diameter.
Leaves sinuate dentate, sometimes lobed near the base, velvety to the touch beneath; peduncles of fruit longer than the petioles[2 Q. bicolor.]
Leaves irregularly lobed, harsh or rarely velvety or smooth to the touch beneath; peduncles of fruit shorter than the petioles.
Cup of fruit fringed; apex of lobes of leaves generally rounded; trees of lowland[7 Q. macrocarpa.]
Cup of fruit not fringed; apex of lobes of leaves generally acute; trees of swamps in the extreme southwestern counties of Indiana[8 Q. lyrata.]
Bark dark, tight and furrowed; leaves with bristle tips; fruit maturing the second year.
Leaves entire[9 Q. imbricaria.]
Leaves more or less deeply lobed, the lobes and teeth conspicuously bristle pointed.
Mature leaves smooth beneath, except tufts of hairs in the axils.
Leaves lobed to about the middle, the lateral lobes broadest at the base; cup saucer-shaped; nut about 1.5-2 cm. in diameter; terminal buds reddish[10 Q. rubra.]
Leaves lobed to beyond the middle, frequently those grown in dense shade not so deeply lobed, some or all of the lateral lobes broadest toward the apex.
Cup saucer-shaped, rarely enclosing the nut for more than 1/3 its length; trees of the low lands and swamps.
Leaves glossy above; blades usually 10-12 cm. long; cups usually 1.5 cm. or less broad; terminal buds chestnut brown[11 Q. palustris.]
Leaves dull above, usually about 15 cm. long; cups 1.5-2.5 cm. broad, rarely as narrow as 1.5 cm.; terminal buds grayish brown[12 Q. Schneckii.]
Cup hemispheric, generally enclosing the nut for half its length; trees of the uplands.
Inner bark yellowish or orange; kernel of nut yellowish or orange, and very bitter.
Terminal buds usually 5 mm. or less in length, ovoid and generally blunt, reddish-brown; scales of cup closely appressed; trees local in the extreme northwest part of the State[13 Q. ellipsoidalis.]
Terminal buds usually longer than 6 mm., usually angled and sharp-pointed; scales of cup not closely appressed; trees of all parts of the State[14 Q. velutina.]
Inner bark reddish or gray; kernel white and not very bitter[15 Q. coccinea.]
Mature leaves more or less pubescent on the whole under surface.
Leaves grayish or yellowish pubescent beneath; scales of cup with a reddish-brown border; nut enclosed for about 1/3 its length[16 Q. falcata.]
Leaves brownish or rusty pubescent beneath, sometimes appearing grayish; scales of cup without a dark border; nut enclosed for about half of its length.
Leaves expanded at the apex, and generally with three lobes; mature twigs generally scurvy-pubescent[17 Q. marilandica.]
Leaves deeply lobed; mature twigs generally glabrous[14 Q. velutina.]

1. Quercus álba Linnæus. White Oak. [Plate 40.] Large trees with gray, fissured bark, flaky on the branches, on the upper part of the trunks of some trees the bark loosens at the fissures and peels back, forming flat strips which remain attached at one side; twigs at first hairy, becoming smooth; leaves mostly obovate in outline, generally 8-20 cm. long on petioles 0.5-2 cm. long, more or less deeply lobed into 5-9 lobes, the lobes ascending and generally blunt and entire, sometimes the lobes have one or two secondary lobes, leaves narrowed and oblique at the base, smooth above, smooth and glaucous beneath; acorns sessile or on stalks up to 2 cm. long; nuts quite variable on different trees as to size and shape, ovoid or oblong, 18-30 mm. long; cup flat on the bottom, tuberculate and encloses about 1/4 of the nut; scales blunt and woolly.

Distribution.—Maine, southern Ontario, Minnesota south to Florida and Texas. Found in all parts of Indiana. In point of number it is exceeded only by the beech, although it has a more general distribution. It is adapted to many types of soil, and is found in almost all situations in Indiana except in very wet soils. It is sparingly found in the sand dune area. On the clay soils of the northern part of the State it is a frequent to an abundant tree, and in the southern part of the State it often forms complete stands on the slopes of the hills.

The white oak is one of the largest and possibly the longest lived tree of Indiana. While it is able to adapt itself to many situations, it grows to the largest size in a porous, moist and rich soil.

Remarks.—Wood heavy, hard, close-grained, tough, strong and durable. On account of its abundance, and wide range of uses, it has always been the most important timber tree of Indiana.

Formerly the woods were full of white oak 1-1.5 meters (3-5 ft.) in diameter, but today trees of a meter (3 ft.) in diameter with long straight trunks are rare indeed. Michaux who traveled extensively in America 1801-1807, while the whole Mississippi Valley was yet a wilderness, remarks: "The white oak is the most valuable tree in America." He observed the ruthless destruction of this valuable tree, and predicted that the supply would soon be depleted, and that America would be sorry that regulations were not adopted to conserve the supply of this valuable tree. Michaux's prediction has come true, and yet no constructive measures have been provided to insure the Nation an adequate supply of this timber. It should be remembered that it requires two to three hundred years to grow a white oak a meter in diameter, and if we are to have white oak of that size in the next generation the largest of our present stand must be spared for that harvest.