2. Isotria verticillata (Muhl. ex Willd.) Raf. (large whorled pogonia)

Pl. 114 c, d; Map 468

Flowering stems 15–30 cm tall, green. Flowers with stalks 12–35 mm long. Sepals 30–60 mm long, at least twice as long as the petals, purplish green, linear‑attenuate. Lateral petals 14–22 mm long, yellowish green, often purple tinged near the tips, narrowly obovate. Lip 13–18 mm long, oblong to obovate, yellowish green, the lateral lobes purple tinged, the middle lobe often white, broadly rounded, with a longitudinal, yellowish green crest, this sometimes purple tinged. Capsules with stalks 20–60 mm long. 2n=18. April–May.

Uncommon in the southeastern quarter of the state, in the Ozark and Ozark Border Divisions, and in Crowley’s Ridge (eastern U.S. and adjacent Canada west to Texas). Mesic upland forests on acidic substrates, in bottoms and on lower slopes of ravines; also in dry upland forests on chert and sandstone.

This species is more easily noticed than I. medeoloides. It tends to occur in colonies, as the plants produce long, horizontal roots that can give rise to new aerial stems from their tips. The flowers are pollinated by small bees.