Height: 15–45 cm (6–18 in.). Upper stem sparsely branched, hair growing upwards flush with stem, base reddish.
Flower: Regular (actinomorphic), 3 mm (0.12 in.) wide. Corolla yellowish white, fused, narrowly funnel-shaped, 5-lobed, hairy. Upper part of calyx-tube bluish. Calyx fused, deeply 5-lobed, lobes narrow, needle-like. Stamens 5. Gynoecium fused, single-styled. Inflorescence a scorpioid cyme, flowers with subtending bracts, subtending bracts resemble stem leaves.
Leaves: Alternate. Basal leaves stalked, winged, upper stem leaves stalkless. Blade narrowly ovate–lanceolate–oblanceolate, with entire margin, both sides hairy.
Fruit: 4-parted schizocarp. Mericarps greyish brown, with granular surface, 2–3.5 mm (0.08–0.14 in.) long.