Stems simple or branched, 7–120 cm; branches ascending, spreading, or arching, quadrangular-ridged to winged distally, glabrate or scabridulous to sparsely scabrous, especially on angles or also on faces near nodes. Leaves spreading to ascending; blade narrowly linear to linear or linear-lanceolate, 7.5–50 x 0.5–4(–5) mm, not fleshy, margins entire, abaxial midvein sometimes scabrous, adaxial surface scabrous; axillary fascicles absent or shorter than subtending leaves. Inflorescences racemes, short to elongate, flowers 1 or 2 per node; bracts longer than pedicels. Pedicels spreading-ascending, 1–5(–6) mm, glabrous, rarely scabrous. Flowers: calyx tubular-campanulate to hemispheric, tube (2–)3–5 mm, glabrous, rarely scabrous on major veins, lobes triangular, lanceolate, or triangular-subulate, not keeled, 0.8–3(–5) mm; corolla pink to rosy pink, with 2 yellow lines and red spots in abaxial throat or these pale or absent, 9–36 mm, throat pilose externally and villous within across bases and sinus of adaxial lobes, lobes: abaxial spreading to reflexed or projected to somewhat spreading (small-flowered plants), adaxial erect to reflexed, 2.5–11 mm, pilose externally; proximal anthers parallel to filaments, distal oblique or perpendicular to filaments (parallel in small-flowered plants), pollen sacs 0.9–4.5 mm; style included or exserted, 6.5–21 mm. Capsules globular, 4–6(–7) mm. Seeds dark brown, 0.7–1.4 mm. 2n = 28.
Man., N.B., N.S., Ont., Que., Ala., Ark., Conn., D.C., Del., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Maine, Mass., Md., Mich., Minn., Miss., Mo., N.C., N.H., N.J., N.Y., Nebr., Ohio, Pa., R.I., S.C., Tenn., Tex., Va., Vt., W.Va., Wis.
Varieties 2 (2 in the flora).
Reports of Agalinis purpurea from the West Indies have not been confirmed.
|1||Corollas 18–36 mm, lobes (4–)5–11 mm; styles strongly exserted; distal anthers perpendicular to filaments; stems 40–120 cm, branches ascending, spreading, or arching.||Agalinis purpurea var. purpurea|
|1||Corollas 9–20 mm, lobes 2.5–5(–6) mm; styles included or slightly exserted; distal anthers oblique or parallel to filaments; stems 7–60 cm, simple or branches ascending.||Agalinis purpurea var. parviflora|