Stems purplish black when young, prostrate to ascending, rooting at nodes, glabrous or with very sparse bifarious hairs. Leaves obovate to oblanceolate, widest about or above the middle, shallowly toothed, obtuse to broadly subacute at apex, green beneath, (0.5)-0.8-2 × (0.3)-0.6-1 cm. Inflorescences many-flowered, (7)-10-15—(20) cm long; peduncle stout, (5)-6-10 cm, peduncle, rachis and pedicels glabrous or sometimes uniformly glandular- hairy. Bracts and calyx glabrous or sparsely glandular-ciliate. Corolla with pale mauve ring at throat, anterior lobe <2 mm wide. Capsule black or dark purplish brown, 2.5-3.5 × 2.5-3.5 mm.

Subspecies ab his characteribus distinguenda: Culmi prostrati vel adscendentes, juvenes atro-purpurei, glabri vel parce villosi. Folia obovata vel oblanceolata, apice obtusa vel late subacuta. Pedunculus, rachis pedicellique glabri vel glanduloso-villosi. Corollae faux pallidemalvaceo annulo circumdata, lobus anticus quam 2 mm angustior.