16a. Calystegia spithamaea (Linnaeus) Pursh subsp. spithamaea
[E F]
Plants 10–30(–50) cm; habit erect, ± lax. Herbage glabrate to pubescent. Leaf blades elliptic to broadly elliptic, ultimately ± flat, base cuneate, rounded, or lobed, lobes to 4(–6) mm. Flowers: corolla 41–63(–67) mm; stamens (21–)24–32(–34) mm. 2n = 22.
Flowering May–Aug. Open grasslands, sandy and stony sites, woods; Conn., Del., Ill., Ind., Iowa, Ky., Maine, Md., Mass., Mich., Minn., Mo., N.H., N.J., N.Y., N.C., Ohio, Pa., Tenn., Vt., Va., Wis.
