Stems branched, 37–80 cm; branches ascending-spreading, terete proximally, obtusely quadrangular-ridged distally, glabrate or sparsely scabridulous. Leaves mostly spreading, proximal often +/- reflexed; blade filiform to narrowly linear, 10–36 x 0.3–1 mm, margins entire, adaxial surface scabridulous; axillary fascicles absent or shorter than subtending leaves. Inflorescences racemes, flowers 1 or 2 per node; bracts shorter than pedicels. Pedicels ascending, 9–30 mm, scabridulous. Flowers: calyx hemispheric, tube 3–5 mm, glabrous, lobes triangular-subulate to subulate, 0.4–0.8(–1.3) mm; corolla pink to rose pink, with 2 yellow lines and red spots in abaxial throat, 14.5–24 mm, throat glabrous externally, sometimes pilose proximal to sinuses, glabrous within across bases of adaxial lobes, sparsely villous at sinus, lobes: abaxial spreading to recurved, adaxial arched over anthers, 4.5–9 mm, unequal, abaxial 5.5–9 mm, adaxial 4.5–6 mm, glabrous externally; proximal and distal anthers perpendicular to filaments, pollen sacs 3–4 mm; style exserted, 13–17 mm. Capsules globular to obovoid-globular, 5–7 mm. Seeds dark brown, 0.8–1.8 mm. 2n = 26.
Phenology: Flowering Aug–Oct.
Habitat: Grasslands, open rocky slopes, calcareous, clay or sandy soils.
Elevation: 200–600 m.
Agalinis edwardsiana is found mostly on the Edwards Plateau. The species is distinguished from A. strictifolia by the nearly straight to rounded abaxial corolla throat of A. edwardsiana and the often strongly upcurved abaxial corolla throat of A. strictifolia.