Stems simple or branched, 30–100 cm; branches ascending, obtusely quadrangular proximally, quadrangular-ridged distally, scabrous. Leaves spreading-ascending; blade narrowly linear to linear, 14–35(–40) x 0.6–1.5 mm, not fleshy, margins entire, abaxial midvein scabrous, adaxial surface scabrous; axillary fascicles usually to 1/2+ as long as subtending leaves, sometimes absent. Inflorescences racemes, flowers 1 or 2 per node; bracts shorter than or both shorter and longer than pedicels. Pedicels ascending, often arching upwards distally, 6–30 mm, scabrous, sometimes only proximally. Flowers: calyx funnelform to obconic, tube 3–5 mm, glabrous, lobes recurved, triangular-subulate, 0.6–1.5 mm; corolla dark pink, with 2 yellow lines and dark purple spots in abaxial throat, 15–26 mm, throat pilose externally and glabrous within across bases of adaxial lobes, sparsely villous at sinus, lobes: abaxial projecting-spreading, adaxial arched over anthers, 2–6 mm, unequal, abaxial 4–6 mm, adaxial 2–4 mm, glabrous externally; proximal anthers perpendicular to filaments, distal oblique or perpendicular to filaments, pollen sacs 3–4 mm; style exserted, 12–18(–20) mm. Capsules globular, 5–7 mm. Seeds dark brown to nearly black, 0.8–1.6 mm. 2n = 26.
Phenology: Flowering late Aug–early Oct.
Habitat: Dry, open woodlands, dry to xeric sandy terrace communities above streams, dry roadsides, open sandy habitats.
Elevation: 0–300 m.
Ark., La., Miss., Okla., Tex.
Agalinis homalantha is a common component of dry to xeric, open communities in Oklahoma and Texas and to a lesser extent in Louisiana. In Arkansas, populations are found from Fort Smith along the Arkansas River to the Mississippi River and southward to Bolivar County, Mississippi, where they are often associated with sandy terraces just downstream from dams and levees. Flooding of the sandbanks often carries seeds of A. homalantha well away from the streams, where it thrives in recently disturbed, weedy, sandy areas (J. F. Hays 1998).
Agalinis homalantha is distinguished from A. tenuifolia by its scabrous branches and pedicels; short, arched adaxial corolla lobes; prominent, wider yellow lines in the corolla; larger anthers with longer awns; and larger seeds.