2. Nyssa biflora Walter (swamp black gum, swamp tupelo)

N. sylvatica Marshall var. biflora (Walter) Sarg.

Map 1612

Plants large trees to 25 m tall, the trunk usually tapered from a swollen and/or buttressed basal portion, the bark relatively thick, finely to more commonly deeply fissured, the ridges often breaking into irregular plates, gray to brown or black. Twigs reddish brown to gray, relatively slender to moderately stout. Leaves with petioles 0.5–1.5 cm long, these usually densely pubescent with spreading, sometimes tangled, mostly 2-branched hairs, sometimes only on the upper surface. Leaf blades (2–)4–8 cm long, 1.5–3.5 cm wide, lanceolate to elliptic or oblanceolate, the margins entire and sometimes also hairy, often minutely curled under, mostly tapered at the base, rounded or angled to short-tapered to a bluntly or less commonly sharply pointed tip, the upper surface glabrous, often 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 dense, subumbellate clusters 0.7–1.2 cm in diameter, the inflorescence stalk 1.5–2.0 cm long. Pistillate flower(s) 1 or 2 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 to ellipsoid, 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.

Uncommon, known thus far from a single historical collection from Dunklin County (southeastern U.S. west to Missouri and Texas). Habitat unknown but presumably swamps.

In most leaf and floral characters N. biflora resembles N. sylvatica, and some botanists have treated it as a variety of that species (Eyde, 1963, 1966; Gleason and Cronquist, 1991; Wen and Stuessy, 1993). Burckhalter (1992) studied taxonomic relationships in temperate North American Nyssa and concluded, based on morphological variation in various habitats and differences in flavonoid chemistry, that the two taxa should be considered separate species.