4. Nyssa biflora Walter, Fl. Carol. 253. 1788.
Swamp black or sour gum Swamp black or sour gum
Nyssa sylvatica Marshall subsp. biflora (Walter) A. E. Murray; N. sylvatica var. biflora (Walter) Sargent
Trees, 10–30 m, <base often buttressed in larger individuals, proximal limbs spreading to slightly drooping>, crown irregular; bark irregularly fissured; twigs glabrous or puberulent. Leaves: petiole 7–10 mm; blade oblanceolate to narrowly elliptic, rarely ovate, 3.7–7.2 × 1.6–3.5 cm, subcoriaceous, base cuneate to rounded, margins usually entire, rarely coarsely dentate distally, apex obtuse to acute, abaxial surface glabrous or puberulent (primarily along veins), adaxial surface glabrous. Inflorescences: peduncle 3.2–5.5 cm, sparsely hairy; staminate (1–)2–8-flowered, pistillate and bisexual 1–3-flowered. Staminate pedicels present. Flowers: ovary glabrous. Drupes usually black, sometimes to blue, glaucous, ovoid, 7–14 mm, smooth; stone 7–9 mm, with several low, rounded longitudinal ridges.
Flowering spring. Swamps, flatwood depressions and ponds, bogs, wet streamheads, seepage slopes, often in sites with standing water during part of the year or with organic soils saturated year-round, less often in mesic forests; 0–100(–200) m; Ala., Ark., Del., Fla., Ga., Ill., Ky., La., Md., Miss., Mo., N.J., N.C., S.C., Tenn., Tex., Va.