Annual erect herb 5–35 cm. high. Stem branched from the base or a little above, 4-winged like the ascending branches, the wings conspicuously scabrous. Leaves 7–45 × 1·5–10 mm., decussate, broadly lanceolate, obtuse or subacute at the apex, margin scabrous and ± nvolute, cordate at the base and contracted a little above, greyish green or dark green, 1 -nerved, the nerve impressed above, prominent and scabrous beneath. Dichasia (1)3-many-flowered, pedunculate, the peduncle 1–8 mm. long; bracteoles up to 1·25 mm. long, scarious, with a green midrib and scabrous margin. Flowers 4(5)-merous. Calyx 3–3·5 mm. long, narrowly tubular, a little constricted above, reddish, conspicuously longitudinally ribbed, minutely scabrous especially along ribs; lobes c. 0·75 mm. broad and 0·25 mm. high, deltate; appendages spreading, c. 0·5 mm. long, a little longer than the lobes. Petals c. 1·5 × 0·75 mm., ovate-lanceolate, with a conspicuous midrib, caducous, violet. Stamens 8(10), included, inserted in 2 rows at c. 1/3 of the calyx-tube length; anthers c. 0·2 mm. long, globose. Ovary 1 × 0·6 mm., ellipsoid, 2-locular; style (with stigma) c. 0·25–0·5 mm. long, included. Capsule included, many-seeded subsepticidal; operculum thick, persisting attached to the voluminous placentas. Seeds c. 0·25 mm. in diam., brownish.
