Rhodora 20: 71. 1918.
Stems simple or branched, 15–82 cm; branches ascending, subterete, retrorsely short-sericeous and hispid. Leaves spreading-ascending; blade triangular-ovate, 16–35 x 10–45 mm, margins 2-pinnatifid with 1–3 pairs of lobes, pinnatifid distally, margins and midvein hispid, siliceous, adaxial surface scabrous or glabrous; axillary fascicles absent. Inflorescences spikelike racemes, dense, flowers 1 or 2 per node; bracts longer than pedicels, margins pinnatifid. Pedicels erect, 0.5–2 mm, scabridulous. Flowers: calyx campanulate, tube 4–7 mm, densely, finely scabridulous and hispid, lobes lanceolate, 7–11 mm, unequal; corolla pink to pale pink, usually without 2 yellow lines and with red spots in abaxial throat, 18–33 mm, throat pilose externally and villous within at sinus and/or across bases of adaxial lobes, lobes: abaxial spreading, adaxial erect, 5.5–11 mm, abaxial sparsely pilose externally, adaxial shorter than abaxial, glabrous externally; proximal anthers parallel to filaments, distal oblique or perpendicular to filaments, pollen sacs 1.5–3.8 mm; style exserted, 16–26 mm. Capsules ovoid-obovoid, 7–10 mm. Seeds dark brown to black, 1.8–3 mm. 2n = 26.
Phenology: Flowering Aug–Sep.
Habitat: Prairies, grassy roadsides, pastures, well-drained calcareous soils.
Elevation: 100–900 m.
Kans., Okla., Tex.
Agalinis densiflora is distinguished from other species of the genus by the pinnatifid leaves, yellow color of the proximal, tubular portion of the corolla, and the asymmetric calyx. The adaxial wall of the calyx tube is flat, the abaxial wall is convex, and the filaments of the shorter pair of stamens are narrower than those of the longer filaments (as the filaments are in A. auriculata).
Agalinis densiflora is known from north-central Texas northward to northeastern Kansas.