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.
