Perennial. Stems weak, ascending, 4-angled, glabrous, 15-60-(100) cm long. Lvs green, sessile, connate in pairs, narrow-oblanceolate to narrow-lanceolate below, narrow-lanceolate or becoming linear-lanceolate above, tapering gradually to acute apex and sparsely ciliate or glabrous base, (10)-15-30-(50) × 3-5-(8) mm; margin flat; marginal vein obscure or 0. Infl. a terminal dichasium, lax, (10)-20-60-flowered. Bracts ovate-acuminate to subulate, keeled, 4-7 × 1-3 mm; margins scarious, ciliate. Pedicels slender, patent, glabrous, 10-30-(50) mm long. Sepals narrow-triangular, acute, 3-veined, 4-7 mm long; margins scarious, ciliate. Petals 4-9 mm long, c. = or slightly > sepals. Stamens 10 or fewer. Capsule narrow-ovoid, = or > calyx. Seeds dull brown, c. 1 mm long; papillae low, elongate.