Stems widely branched, 20–60 cm; branches ascending, angular distally, scabridulous. Leaves spreading or reflexed or recurved; blade filiform, 15–35 x 0.3–0.6 mm, margins entire, siliceous, adaxial surface scabrellous; axillary fascicles absent. Inflorescences racemes, flowers 1 or 2 per node; bracts equal to or shorter than pedicels. Pedicels spreading-ascending, 7–22 mm, proximally scabridulous. Flowers: calyx hemispheric-campanulate, tube 3.5–5.5 mm, glabrous, lobes triangular-subulate, 0.8–1.7 mm; corollas rose purple, with 2 yellow lines and red spots in abaxial throat, 17–30 mm, throat pilose externally and glabrous within across bases of adaxial lobes, lobes spreading, 6–9(–11) mm, glabrous externally; proximal anthers parallel to filaments, distal perpendicular to filaments, pollen sacs 2.5–3.8 mm; style exserted, 12–16.5 mm. Capsules unknown. Seeds unknown.
Phenology: Flowering Oct.
Habitat: Oak woods, dry loamy soils.
Elevation: 50–100 m.
Agalinis caddoensis is known only from two collections made by F. W. Pennell in 1913 and is most similar morphologically to A. navasotensis; see 22. A. navasotensis for a comparison. Agalinis caddoensis should be expected in northwestern Louisiana and eastern Texas and likely flowers in September as does A. navasotensis.