Annual herb, 10-50 cm. Stems ascending or erect, somewhat fleshy, unbranched, green or purplish (? fistulose), glabrous or with glandular hairs on inflorescence axis, leafy, thick or thin. Leaves in whorls of 2-6, linear to linear lanceolate, sessile, very variable in dimensions from 2-5 cm x c. 0.5 mm, glabrous, densely gland-dotted below, entire to distantly serrulate, ± cordate at base. Inflorescence a continuous terminal spike, 3-10 cm x 8 mm, pubescent; verticillasters many-flowered. Bracts c. 2 mm, purplish, deciduous. Calyx purplish c. 1.5 mm with 5 ± equal teeth, campanulate, with short eglandular, with or without glandular hairs and sessile oil globules; teeth somewhat connivent in fruit. Corolla pink to lilac, 3.5 mm, glabrous, scarcely bilabiate, with 4 unequal short lobes. Staminal filaments densely covered with long spreading purplish hairs. Style deeply 2-lobed. Nutlets c. 0.8 x 0.7 mm pale brown, ovoid.