3. Nyssa sylvatica Marshall (black gum, sour gum, black tupelo)

N. sylvatica var. carolina (Poir.) Fernald

N. sylvatica var. dilatata Fernald

Map 1613, Pl. 369 k, l

Plants large trees to 30 m tall, the trunk not or only slightly swollen and never buttressed toward the base, the bark relatively thick, finely to more commonly deeply fissured, the ridges usually breaking into irregularly hexagonal plates on older trunks, gray to brown or black. Twigs reddish brown to gray, usually relatively slender. Leaves with petioles 0.5–2.0 cm long, these moderately to densely pubescent with spreading, sometimes tangled, mostly 2-branched hairs, sometimes only on the upper surface or undersurface. Leaf blades 4–15 cm long, 2–6 cm wide, elliptic to obovate, occasionally narrowly elliptic or oblanceolate, the margins entire or rarely with 1 to few, coarse, broadly triangular, spreading teeth, sometimes also hairy, often minutely curled under, broadly angled or tapered at the base, rounded or angled to more commonly short-tapered to a usually sharply pointed tip, the upper surface glabrous, somewhat shiny, the undersurface sparsely to moderately hairy, especially along the main veins, pale green but not glaucous. Staminate flowers in short, dense racemes or appearing as umbellate clusters 0.7–2.5 cm in diameter, the inflorescence stalk 1–2 cm long. Pistillate flowers 2–4(5) per inflorescence, the inflorescence stalk 2–5 cm long. Petals 0.5–1.5 mm long, oblong, usually rounded at the tip. Fruits 0.8–1.2 cm long, ovoid, purplish blue to nearly black, with scattered, minute, white spots, glaucous, bitter, the stone with 8–12 broad, rounded, shallow longitudinal ridges. 2n=44. April–May.

Scattered to common in the Ozark, Ozark Border, and Mississippi Lowlands Divisions (eastern U.S. west to Wisconsin and Texas; Mexico). Bottomland forests, mesic to dry upland forests, savannas, swamps, sloughs, banks of streams, rivers, and spring branches, and margins of sinkhole ponds; also old fields, railroads, and roadsides; usually in acidic soils.

Black gum trees are grown as ornamentals for their shiny foliage, which turns various shades of purple, red, orange, and yellow in the autumn. Various authors have treated N. sylvatica as comprising two to several varieties. On the one hand, some of these (var. caroliniana, var. dilatata) are merely morphological extremes for various characters. Some others probably are best treated as separate species (Burkhalter, 1992). The latter group includes N. biflora (treated above) and N. ursina Small (N. sylvatica var. ursina (Small) J. Wen & Stuessy; shrubs or dwarf trees endemic to northwestern Florida).