American columbo

Swertia caroliniensis (Walter) Kuntze

Herbs monocarpic, 10–25 dm, glabrous or stems and leaves puberulent. Stems 1. Leaf blades not white-margined; basal spatulate to elliptic or narrowly obovate, 20–45 × 3–10 cm, apex rounded to acute; cauline leaves whorled, blade oblong-lanceolate, 10–32 × 3–7 cm. Inflorescences elongate, open proximally, ± dense distally. Flowers: calyx 6–16(–25) mm; corolla pale yellowish green, purple-dotted and sometimes suffused with pale purple, 10–21 mm, lobes elliptic-oblong, apex short-acuminate; androecial corona of trichomes and deeply fringed scales to 3 mm; style slender, distinct; nectaries and foveae 1 per lobe, foveae round, opening directly adaxial to nectary, without a differentiated area on the corolla surface, rim ± evenly fringed all around. 2n = 78.

Flowering late spring–early summer. Deciduous, ± open woods, often ravines, calcareous soils; 100–700 m; Ont.; Ala., Ark., Ga., Ill., Ind., Ky., Mich., Miss., Mo., N.Y., N.C., Ohio, Okla., Pa., S.C., Tenn.

An old report of Frasera caroliniensis from Louisiana is plausible, but no documentation is known.