2. Corallorhiza wisteriana Conrad (coral root)

Pl. 111 a, b; Map 459

Flowering stems 10–35 cm long, the base slightly thickened, the raceme with 8–20 flowers. Sepals and lateral petals 6–8 mm long, greenish purple, rarely yellowish green. Lip 5–6 mm long, white, usually with reddish purple spots. Fruits 8–12 mm long. April–May, rarely September.

Scattered throughout Missouri (eastern U.S. and adjacent Canada west to Oklahoma; Mexico, Central America). Mesic upland and bottomland forests, frequently on acidic substrates; also sometimes at the edges of glades in rocky soil.

Earlier reports of C. trifida Châtel. var. verna (Nutt.) Fernald from Lawrence and Warren Counties (Steyermark, 1963; Summers, 1981) were based upon misdetermined specimens of a rare, albino form of C. wisteriana. In these plants, the purple pigment is absent, thus the stems are yellow, the sepals and lateral petals are yellowish green, and the lips of the flowers are pure white, as in C. trifida. However, the flower morphology of the Missouri plants, particularly the position of the lateral sepals and petals, the shape of the lip, and the lack of a pair of pronounced lateral lobes on the lip, differentiate them from true C. trifida. That species is circumboreal, ranging south to northern Illinois and Indiana in the midwestern United States.