Triodanis perfoliata (L.) Nieuwl.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Erect, 1–10 dm, simple or with few long branches, often floriferous to near the base, ± scabrous or hairy at least below; lvs (and floral bracts) sessile and cordate-clasping, rotund-ovate or broader, usually toothed, palmately veined, 0.5–3 cm, nearly as wide, or wider, or some of the lower ones narrower; cal cleft to the hypanthium, the lobes narrowly triangular-acuminate, 5–8 mm in open fls; upper fls with deep purple to pale lavender cor 8–13 mm, the tube 2–4 mm; frs oblong or narrowly obovoid, those of cleistogamous fls 4–7 mm, those of open fls to 1 cm, all bilocular or trilocular; pores usually 1–1.5 mm below the tip of the fr; seeds 0.5–0.6 mm; 2n=60. Various habitats, often in disturbed sites; Me. to B.C., s. to trop. Amer. May, June. (Specularia p.)