4. Rhus typhina L. (staghorn sumac)

R. hirta (L.) Sudw.

Schmaltzia hirta Small

Pl. 201 d; Map 834

Plants tall shrubs or small trees 2–6 m tall, with stout branches. Young branches, petioles, and leaf rachis densely pubescent with woolly or felty hairs. Leaves pinnately compound, with 9–25 leaflets, rarely 2 times pinnately compound, 9–40 cm long, the petioles 3–10 cm long, densely woolly or felty, the rachis not winged. Leaflets 7–10 cm long, 1.0–4.5 cm wide, (appearing dissected in bipinnate forms), lanceolate to narrowly oblong, sessile or very short-stalked, the margins toothed, the upper surface dark green, glabrous or nearly so, shiny, the undersurface light green, moderately to densely hairy along the veins, also glaucous. Inflorescences terminal, dense, ovoid panicles, 7–25 cm long, 3–4 cm wide. Sepals 1.2–1.5 mm long, narrowly ovate, sharply pointed at the tip. Petals 1.5–2.5 mm long, oblong-oblanceolate, rounded at the tip, greenish yellow, sparsely hairy on both surfaces. Fruits 4–5 mm long, 4–5 mm wide, somewhat flattened, red, with dense, slender, straight, red hairs 1–2 mm long. 2n=60. June–July.

Introduced, known thus far from Greene County and the St. Louis metropolitan area (eastern U.S. west to Wisconsin and Mississippi, introduced farther west; Canada). Railroads and open, disturbed areas.

The name R. typhina L. is widely used and deeply entrenched in the botanical literature, but for a time it appeared that, as a consequence of a minor change in wording in a past International Code of Botanical Nomenclature, an older name, R. hirta, might have to be used for this taxon (Reveal, 1991b; Kartesz and Gandhi, 1991). The basis for this name, Datisca hirta L., was based upon a monstrous cultivated form of the species in which the inflorescence had reverted to leaves. Fortunately, that epithet was rejected formally from any further use at the 1999 International Botanical Congress in St. Louis (Greuter et al., 1999), thus stabilizing the use of the name R. typhina.

The original reports of this species in Missouri were of escaped plants of R. typhina f. dissecta Rehder (var. laciniata A.W. Wood), a cultivar with dissected, 2 times pinnately compound leaves that is sometimes planted as an ornamental in gardens.