Part 2

Identification is further complicated because hybrids commonly occur among the oaks.

The oaks are divided into two main groups: the white oaks and the red (or black) oaks. The white oaks have leaves with rounded lobes and no bristles; acorns mature the first fall, and the inner surface of the shell is glabrous. White oak, chestnut oak, and post oak belong to this group. The red oak group is characterized by bristle-tipped leaf lobes in such species as Shumard, southern red, northern red, cherrybark, and black oak. The red oak group also includes non-lobed species such as water, laurel, and willow oak, which usually have entire margins. Blackjack oak leaves usually lack lobes and bristles, but leaves with terminal lobes occasionally occur and may have one bristle per lobe. Acorns mature the second fall, and the inner surface of the shell is pubescent.

Southern Red Oak, Quercus falcata Michx., and its variety Cherrybark Oak, Q. falcata var. pagodaefolia Ell., have almost identical acorns, but they can be distinguished by other characteristics. The leaf base of southern red oak is somewhat bell-shaped, but that of cherrybark is not. Southern red oak forms heavy ridges of bark; cherrybark does not.

The distinctive feature of Black Oak, Q. velutina Lam., is its yellow-orange inner bark. Its leaves take three forms. Seedlings to small saplings have a “bear-paw” leaf with only a suggestion of lobing. Lower leaves on large trees also have little lobing, but leaves from the middle and upper crown are clearly lobed. The uppermost leaves, which have seven lobes and deep sinuses, are usually illustrated as typical.

Scarlet, Q. coccinea Muenchh., Northern Red, Q. rubra L., and Shumard Oak, Q. shumardii Buckl., are difficult to distinguish. Northern red oak leaves have shallow sinuses and a dull-green upper surface with little or no pubescence in the vein axils on the underside. Shumard oak leaves have a glossier surface, shallow to deep sinuses that are usually wider than the adjacent lobes, and definite hairiness at the vein axils. The sinuses of scarlet oak are also usually wider than their adjacent lobes, which are usually toothed. Both Shumard and scarlet oak have outstanding fall coloration.

Blackjack Oak, Q. marilandica Muenchh., can be recognized by its leathery, usually entire, broadly obovate leaf, which has a rusty undersurface. The branches are stout, irregular, gnarled, drooping to horizontal.

Laurel Oak, Q. laurifolia Michx., and Water Oak, Q. nigra L., are similar in size and shape, but water oak has oblong-obovate or spatula-shaped leaves gradually narrowed to a wedge-shaped base. Laurel oak leaves are elliptic to oblong-ovate. Laurel oaks tend to shed leaves late and thus may retain about 30 to 50 percent of their lower leaves after water oaks are bare. Some recent authors separate the laurel oaks into two species, upland laurel oak, Q. hemisphaerica Bartr., and swamp laurel oak, Q. laurifolia Michx.

White Oak, Q. alba L., has a thin, light green leaf with a light glaucous bloom at maturity; it is oblong or ovate, with rounded lobes and three to five narrow sinuses extending nearly to the mid-rib. The cup scales of the acorn-cup are heavy and distinct.

Post Oak, Q. stellata Wangenh., has stout, irregular branches. The leathery leaves are usually five-lobed; usually the two side lobes are at right angles to the central axis, thus forming a cross-shaped leaf.

Chestnut Oak, Q. prinus L., resembles swamp chestnut oak, Q. michauxii Nutt., a commercially important tree southwide. Chestnut oak is primarily a northeastern tree, extending into the South along the Appalachian highlands into northern Georgia and Alabama where its range overlaps that of swamp chestnut oak, and its leaves lack the dense pubescence found on those of swamp chestnut oak.

Common elms include American Elm, Ulmus americana L., and Winged Elm, U. alata Michx. Both bloom after a freeze breaks dormancy. For example, if a killing frost occurs in the last week of November or the first week of December, American elm will bloom the first week of January. If no killing frost occurs by early December. American elm may not bloom until the third week of January. Winged elm usually blooms 10 days to 2 weeks later than American elm. Small winged elm trees frequently have a corky outgrowth on opposite sides of twigs at least 3 years old. Mature trees often lack this characteristic. The American elm leaf has unequal basal lobing and pubescent or ciliate samaras about 12 mm in diameter; winged elm has a smaller leaf with round to acute leaf bases and a very ciliate samara about 8 mm long.

Young Sugarberry, Celtis laevigata Willd., and Hackberry, C. occidentalis L., trees are readily recognized by a whitish to light gray bark dotted with small corky warts. Older trees often have relatively smooth, light to medium gray bark. Leaf margins of sugarberry are usually entire or indistinctly toothed; the upper half of hackberry leaves are usually conspicuously serrate. Both species produce tiny flowers on the new growth when the leaves are about half normal size. The fruit of sugarberry is orange-red to black; that of hackberry is dark red to nearly black at maturity.

Yellow-poplar, Liriodendron tulipifera L., or tulip tree, has alternate, four- to six-lobed leaves with truncate to distinctly notched apices, a unique feature among American trees. The flowers are tulip-like with red markings on a greenish-yellow background. The fruit is a cone-like aggregate of samaras.

Sweetbay, Magnolia virginiana L., produces moderate-sized trunks on uplands or numerous pole-like suckers in branch bottoms. It is evergreen in the southern part of its range and deciduous in the northern portion. A wind blowing in the crown will expose the silvery underside of the leaves. The white flowers, about 5 to 10 cm in diameter, open for the first time about 3 p.m. and close about 9 p.m. They reopen the next morning and shed their stamens. The fruit is a green pickle-like aggregate of follicles that splits open to reveal red seeds. Sweetbay and yellow-poplar, both members of the Magnolia family, have stipule scars circling the twigs.

Sweetgum, Liquidambar styraciflua L., or redgum, is easily recognized by its alternate, star-shaped, palmately lobed leaves. Some trees have corky outgrowths on the small branches. Its flower consists of several round clusters of stamens arranged in a raceme and a stalked pistillate head that develops into a spiny, woody fruit containing many seeds.

Red Maple, Acer rubrum L., has simple, opposite leaves that are usually glaucous and pubescent. The flowers appear in early February and the fruit is a double samara. The variety A. rubrum var. drummondii (Hook. and Arn.) Sarg., which has densely matted white hairs on the undersides of young leaves, grows in swamps throughout the South. Leaves may have three to five lobes, but southern trees are predominantly three-lobed. For this reason, some authors recognize the southern form as A. rubrum var. tridens Woods.

The leaves of Black Tupelo (blackgum) Nyssa sylvatica Marsh., are alternate, elliptical to obovate, and become spotted early in their development, turning purplish in September before their early shedding. The flowers are small, inconspicuous, and produce a blue-black fruit.

Two of the most common ashes are White Ash, Fraxinus americana L., and Green Ash, F. pennsylvanica Marsh. The most reliable distinction between the two species appears to be samara differences. White ash has a plump, short seed end with the wing practically terminal, whereas green ash has a slender seed end and the wing extends more than halfway down the seed end. White ash usually has a rounded leaflet base, but green ash has wedge-shaped leaflet bases. The undersurfaces of fresh white ash leaves are white, but the color is difficult to detect on dry specimens. Green ash leaves are green on both surfaces, although somewhat paler on undersurfaces.

Key To Hardwoods

The key is composed of paired statements, one true and one false for any given specimen. The guide numbers at the end of statements are used to locate the next pair. Follow the true statements until you come to a common name. If you have made no mistake in interpreting the paired statements, you should arrive at the correct identity of the specimen. Then check the text and illustration.

1. Leaves compound, with blades divided into leaflets 2 1. Leaves simple, blades not divided into leaflets 7 2. Leaves with opposite arrangement on twigs 3 2. Leaves with alternate arrangement on twigs 4 3. Leaflets with rounded bases, conspicuously whitish below when fresh; seed end of samara thickened, wing terminal only White Ash 3. Leaflets with wedge-shaped bases, green below; wing terminal and extending about half the length of the seed Green Ash 4. Buds valvate; buds, fruits, and lower surface of leaflets covered with yellow glandular scales; fruit winged on upper half of husk suture, husk thin, shell thin, meat bitter Bitternut Hickory 4. Buds imbricate, composed of overlapping scales 5 5. Leaflets typically 5, glabrous except for a few hairs on rachis and midribs; bark shaggy Shagbark Hickory 5. Leaflets 7 6 6. Leaflets densely tomentose; bark tight, in diamond-shaped pattern; husk very thick, shell thick, meat sweet Mockernut Hickory 6. Leaflets usually glabrous; bark tight, in diamond-shaped pattern; husk moderately thick, shell thick, meat sweet, husk tardily dehiscent Pignut Hickory 7. Leaves essentially evergreen, large percentage staying on trees until bud expansion, dark green above, silky white pubescent below; flowers white, about 5 to 8 cm in diameter Sweetbay 7. Leaves typically deciduous, or trees retaining some dead leaves to bud expansion 8 8. Leaf margins entire 9 8. Leaf margins lobed or toothed 12 9. Leaves with rusty pubescence below, broadly obovate, leathery bases tapering to cordate or cuneate Blackjack Oak 9. Leaves essentially glabrous or with a few hairs in vein axils 10 10. Leaves shiny below, elliptic or rhombic to spatulate Laurel Oak 10. Leaves dull green below 11 11. Leaves elliptic to obovate, strongly veined with purple spots and discoloration in summer; fruit a drupe Black Tupelo 11. Leaves abruptly obovate, bases wedge-shaped, few lateral veins; fruit an acorn Water Oak 12. Leaf margins toothed 13 12. Leaf margins lobed 16 13. Margins indistinctly toothed, blades narrowly to broadly ovate, base unequal, apex long acuminate Sugarberry 13. Margins distinctly toothed 14 14. Teeth obtuse or rounded, leaf base wedge-shaped, stellate pubescent below Chestnut Oak 14. Teeth sharp 15 15. Leaves normally elliptic, veins prominent below, bases rounded; corky outgrowths on older branches, often lacking on large trees Winged Elm 15. Leaves broadly oval, pinnate veins distinct, margins doubly toothed, bases oblique, unequally rounded American Elm 16. Leaves palmately lobed 17 16. Leaves pinnately or apically lobed 18 17. Leaves opposite, more or less glaucous and pubescent below; fruit a double samara Red Maple 17. Leaves alternate, glabrous below; fruit spherical, woody with spine-like projections; corky outgrowths on branches frequent Sweetgum 18. Blades truncate to notched at apex, 4-lobed; fruit an aggregate of samaras; flower conspicuous, greenish-yellow with red markings Yellow-poplar 18. Blades with acute to obtuse apices 19 19. Blades apically 3-lobed 20 19. Blades pinnately lobed 21 20. Blades broadly obovate, base rounded, rusty pubescent below Blackjack Oak 20. Blades narrowly obovate, base wedge-shaped, mostly glabrous Water Oak 21. Leaves with rounded lobes 22 21. Leaves with bristle tips to lobes and lateral teeth 23 22. Leaves with 7 to 9 lobes, divided nearly to the midrib, whitish below White Oak 22. Leaves with 5 unequal lobes, upper lateral pair larger, squarish, at right angles to midrib, crosslike in appearance, pubescent below Post Oak 23. Leaves pubescent below, whitish to tawny 24 23. Leaves glabrous below or with a few hairs on midrib and in vein axils 26 24. Leaves with 7 to 9 lobes, terminal lobes long, strap-shaped, slightly curved, bases bell-shaped Southern Red Oak 24. Leaves with 7 to 11 lobes 25 25. Leaves oblong, 7 to 11 lobes, base broadly wedge-shaped to truncate, secondary lobes rare; inner bark reddish Cherrybark Oak 25. Leaves broadly oval, 7 to 9 lobes, each lobe with secondary bristle-tipped teeth; inner bark yellow-orange Black Oak 26. Upper leaf surface glossy green 27 26. Upper leaf surface dull green, 7 to 9 lobes, 8 to 22 cm long, round sinuses extending less than half way to midrib Northern Red Oak 27. Leaves with 7 to 9 narrow lobes, sinuses extending more than halfway to midrib Scarlet Oak 27. Leaves with 5 to 7 narrow lobes, rounded sinuses, extending about three-fourths of way to midrib Shumard Oak

Species Described and Illustrated

Mockernut Hickory Carya tomentosa Nutt.

Bark grayish, tight, marked with distinct diamond-shaped ridges and furrows. Branches stout, drooping to spreading and ascending. Twigs 10 to 12 mm in diameter, conspicuous leaf scars. Buds (terminal) 10 to 15 mm long, 5 to 8 mm in diameter, scales imbricate. Leaves alternate, deciduous, odd-pinnately compound, 20 to 40 cm long with 5 to 7 drooping leaflets; yellow hairs and glandular hairs on lower leaflet surface, apex acuminate, margin finely serrate, base obtuse, on very short petiolules. Flowers unisexual, appearing in spring with developing leaves, staminate in 3-parted drooping catkins, pistillate terminal on new growth. Fruit subglobose to obovate, 3 to 5 cm in diameter, husk 1 cm thick, slow to open, shell of nut thick and hard, meat sweet.

Pignut Hickory Carya glabra (Mill.) Sweet

Bark light to dark gray, often blackish, rough and deeply furrowed. Branches stout, drooping to spreading. Twigs 3 to 5 mm in diameter, reddish brown, smooth. Buds ovoid, acute, glabrous, 8 to 12 mm long, scales imbricate. Leaves alternate, deciduous, odd-pinnately compound, 20 to 40 cm long, usually with 7 leaflets; upper pair and terminal largest, 10 to 15 cm long by 4 to 6 cm wide, broadly oval to slightly obovate. Flowers unisexual, staminate in 3-branched catkins appearing about the time of leaf maturity; pistillate terminal on new growth. Fruit oblong to obovoid to obpyriform, 30 mm in diameter by 35 mm long, husk about 3 mm thick, tardily dehiscent, shell of nut thick, meat sweet.

Shagbark Hickory Carya ovata (Mill.) K. Koch

Bark smooth at first, then breaking into long, flat, irregular gray strips, to 5 mm thick, usually attached at the apex, free at the base. Branches stout, smooth, spreading to ascending. Twigs stout, orange-brown, leaf scars large. Buds (terminal), 10 to 20 mm long, 6 to 8 mm in diameter, scales imbricate. Leaves alternate, deciduous, odd-pinnately compound with 5 to 7 leaflets, usually 5 to 18 cm wide and 20 to 35 cm long; lateral leaflets ovate to ovate-lanceolate, terminal leaflet usually obovate, apices acute to acuminate, margins finely serrate, bases wedge-shaped, more or less yellow, pubescent below, gradually becoming glabrous with age. Flowers unisexual, appearing in spring with the developing leaves, staminate in 3-lobed catkins, pistillate on new growth. Fruits subglobose, 2.5 to 6 cm in diameter, husk 3 to 5 mm thick, shell of nut hard and moderately thin, meat sweet.