Hedyotis nigricans (Lam.) Fosberg
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Taprooted perennial; stems few or several, 2–6 dm, ± erect, branched from the base, often somewhat hairy below; lvs linear, sessile, mostly 20–30 × 1–3 mm, 1- nerved, slightly roughened, often with axillary fascicles; middle and upper stipules setiform or bristle- tipped; fls very numerous, on pedicels to 5 mm (some sessile), forming a crowded cymose panicle, heterostylic; sep narrowly triangular, often ciliate, 1–2 mm; cor purple to nearly white, hairy within, funnelform, 5–8 mm, the lobes two-thirds as long as the tube; fr obovoid-cylindric, narrowed to the base, two-thirds inferior, 2.5–3.5 mm; stamens and seeds of no. 1 [Hedyotis canadensis (Willd.) Fosberg]; 2n=18, 20. Dry soil and barrens; O. and Ind. to s. Mich., Io., and Nebr., s. to Fla. and Mex. June–Aug. (Houstonia n.; Houstonia angustifolia)