Perennial. Stems erect, glabrous, ridged or grooved, 10–50 cm tall; branches sometimes sparsely puberulent below. Lvs glabrous. Basal and lower stem lvs withering or falling at fruiting, (3)–5–12–(25) × 1–3–(4) cm, deeply pinnatisect with narrow acute curved teeth on distal edges of pinnae. Upper lvs becoming linear, 3-fid at apex or entire, 5–20–(40) × 1–2–(3) mm; marginal denticles present especially near cuneate lf base. Racemes (3)–5–7–(10) cm long; rachis glabrous; pedicels erecto-patent to patent, (2)–3–4 mm long at fruiting, with hairs in 1 row. Sepals hairy or glabrous, green or purple, 0.7–1 × 0.2–0.3 mm; petals white, minute or 0. Stamens 2. Silicles ovate to rhomboid, 2.4–2.7–(3) × 1.8–2 mm; stigma almost sessile, included in shallow notch; valves green or purple, glabrous. Seed ovoid, brown, not winged, c. 1.4 mm long.
[From: Webb et al. (1988) Flora of New Zealand. Volume 4.]
Flowering: (Jul.)–Oct.–Apr.–(Jun.); Fruiting: (Jul.)–Oct.–Apr.–(Jun.)