2. Nyssa L. (tupelo, sour gum)

(Eyde, 1963; Burckhalter, 1992)

Plants medium-sized to large trees, dioecious, sometimes incompletely so. Winter buds ovoid, with several scales. Twigs with white pith having diaphragms (solid but with numerous differentiated cross-partitions). Leaves alternate, often crowded toward the tips of branches, sometimes appearing nearly whorled on short shoots. Leaf blades with the margins entire or with a few coarse teeth, the secondary veins straight or only slightly arched toward the leaf tip, becoming fine and inconspicuously fused toward the leaf margin. Inflorescences axillary (sometimes appearing terminal or clustered when on short shoots), those of the staminate flowers short, dense racemes or headlike to nearly umbellate clusters, the pistillate flowers solitary or in small clusters of 2–4(5). Flowers mostly imperfect, the staminate and pistillate flowers mostly on separate plants (few to several apparently perfect flowers usually produced per branch on otherwise staminate or pistillate trees). Calyces with the free portion consisting of 5 small, triangular or oblong lobes 0.5–2.0 mm long or more commonly a minute, low rim. Petals 5–10, inserted along the margin of the nectar disc, green to greenish yellow. Stamens 8–15, the slender filaments 3–5 mm long, attached along the margin of the nectar disc, the anthers 0.8–1.2 mm long, oblong, attached at the base. Pistil of 2 fused carpels but 1 carpel usually aborting during development, the ovary glabrous or hairy, with usually 1 locule. Style 1 (sometimes with a short, rudimentary, second style or rarely with a second, fully formed style), relatively stout, bent or reflexed toward the tip, the stigma(s) unlobed. Ovule 1(2) (1 per locule). Fruits ovoid to ellipsoid, dark blue to bluish purple or red. Stone 1(2)-seeded, the seed ovoid or ellipsoid, often somewhat flattened. Five to 10 species, North America, Central America, Asia.

Nyssa sometimes has been treated in a separate family Nyssaceae along with two small Chinese genera, Davidia Baill. and Camptotheca Decne. (Eyde, 1966). The main character separating these genera from the remainder of Cornaceae is the larger number of petals and stamens. The circumscription of some species of Nyssa also has been somewhat controversial (Burckhalter, 1992; Wen and Stuessy, 1993). Nyssa was widely distributed in the Northern Hemisphere during the early Tertiary Period (Eyde, 1988).

Nyssa species are economically important as timber trees, primarily in the southeastern states. The wood is used for plywood, boxes, pallets, furniture, flooring, paper pulp, fishing floats, and handicrafts. The honey from tupelo flowers also is highly esteemed.