Much like no. 1 [Triodanis perfoliata (L.) Nieuwl] and hybridizing freely with it; lvs and floral bracts a little narrower and less veiny, the middle bracts 1.3-1.8(-2.5) times as long as wide; each stem or main branch usually producing only 1 open fl (the terminal one), the other fls cleistogamous; pores reaching the top of the fr, or rarely as much as 0.5 mm below it. Dry soil; s. Va. to Ky. and Mo., s. to Mex., and in S. Amer. May, June. (Specularia b.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.