New Fl. 2: 63. 1837.
Stems often leaning, simple or branched, 30–100 cm, bushy; branches spreading-ascending, subterete proximally to quadrangular-ridged distally, glabrous or sparsely scabridulous distally. Leaves widely spreading to slightly ascending; blade filiform, 18–45 x 0.2–0.8 mm, not fleshy, margins entire, adaxial surface scabridulous; axillary fascicles absent. Inflorescences racemiform, flowers 1 per node, some flowers pseudoterminal; bracts longer than pedicels. Pedicels spreading-ascending, 3–8 mm, glabrous. Flowers: calyx hemispheric, tube 3–5 mm, glabrous, lobes deltate-subulate, 0.2–1 mm; corolla dark-pink to rose-pink, with 2 yellow lines and dark-pink spots in abaxial throat, 18–30 mm, throat pilose externally and villous within across bases and sinus of adaxial lobes, lobes: abaxial spreading, adaxial reflexed-spreading, 6–10 mm, abaxial pilose externally, adaxial glabrous externally; proximal anthers parallel to filaments, distal perpendicular to filaments, pollen-sacs 2.2–4 mm; style exserted, 11–17 mm. Capsules globular, 4–5 mm. Seeds dark-brown to black, 0.5–0.8 mm. 2n = 28.
Phenology: Flowering late Sep–early Nov.
Habitat: Dry to xeric, sandy, gravelly or clay roadsides, pine-oak forests, margins of savannas, disturbed ground.
Elevation: 0–300 m.
Ala., Fla., Ga., La., Miss., S.C., Tenn.
Agalinis plukenetii can be bushy, relatively large, and showy. Agalinis plukenetii is a common component of dry to xeric roadsides in the southern portions of its range. It readily colonizes open, dry ground with very little vegetation. It was reported in South Carolina (F. W. Pennell 1935) based on a specimen that has little label data; its occurrence there is doubtful.