Cardamine lacustris (Garnock-Jones & P. N. Johnson) Heenan, New Zealand J. Bot. 40: 568. 2002; Iti lacustris Garnock-Jones & P. N. Johnson, New Zealnd J. Bot. 25: 603. 1987. TYPE: New Zealand, Henry Creek, E side of Lake Te Anau, 21 May 1971, P. N. Johnson s.n. (holotype CHR 286399).

            Herbs, annual or ephemeral, glabrous or sparsely pubescent. Stems to 5 cm, prostrate, geniculate. Basal leaves petiolate, rosulate, early ones entire, linear-spatulate; cauline leaves and later basal ones pinnatifid, 2–3(–5) cm; petiole 2–12 mm, not auriculate at base; terminal lobe narrowly spatulate, 2–3(–5) mm wide; lateral lobes 1 or 1(–3) on each side, narrowly oblong-spatulate, 4–10 mm. Inflorescence solitary flowers or 2(or 3) from leaf axils; fruiting pedicels 2–5 mm. Sepals oblong, suberect, glabrous, 1.5–2 mm; petals white, suberect, oblong- to obovate-spatulate, 1.8–2.5 × 0.8–1.2 mm; stamens 4(or 6), median pair(s) 1.6–2 mm, lateral 1–1.5 mm; ovules 10–16 per ovary. Fruits ellipsoid to oblong, (1–)2–3(–3.5) × 1–1.7 mm, convex, glabrous. Seeds oblong, ca. 1 mm. 2n = 48.

Flowering: Mar–May.

Habitat: lake shores.

Distribution: New Zealand (South Island).