Cardamine sinuatifolia Heenan

Perennial herb, single rosette or with short lateral branches. Leaves up to 90 mm long, simple or pinnatisect, upright to spreading; lamina 4.0–30.0 × 2.5–15.0 mm, light green, membranous, usually glabrous on abaxial and adaxial surfaces, glabrous or sparsely hairy on margin and petiole; petiole up to 70 mm long, green and usually purple-red in lower half, glabrous to sparsely hairy, hairs 0.3–0.5 mm long, spreading to patent. Terminal pinna 5.0–18.0 × 5.0–15.0 mm, simple, oblong-orbicular, broadly elliptic-orbicular, elliptic-oblong to deltoid-oblong; margin usually shallowly sinuate to occasionally entire, hydathodes indistinct; apex obtuse, hydathode indistinct; base truncate, obtuse, to weakly cordate. Lateral pinnae 1–2(–4), 2.0–8.0 × 1.5–6.0, orbicular, broadly elliptic-orbicular, deltoid-orbicular to rhomboid-orbicular; margin entire, occasionally weakly lobed, hydathodes inconspicuous; apex obtuse; base truncate to cuneate, often oblique; petiolule 0.2–1.0 mm long, often appearing ± sessile. Cauline leaves similar to rosette leaves but smaller, terminal pinna often pinnatifid, pinnae bases attenuate to truncate; terminal pinna up to 10.0 × 6.0 mm, lateral pinnae up to 8.0 × 4.5 mm. Inflorescence with solitary flowers or 1–3 corymbs, corymbs 2–6-flowered; peduncle up to 100 mm long, 0.5–1.0 mm diam. at base, spreading to ascending, glabrous. Pedicels 15.0–115.0 mm long, 0.3–0.7 mm diam., terete, glabrous. Sepals 1.8–2.2 × 0.7–1.2 mm, elliptic-oblong, saccate, green or red-brown; glabrous to sparsely hairy; margin white and membranous, apex obtuse, base truncate. Petals 1–4, or absent; 4.5–5.5 × 2.1–3.0 mm, white, limb obovate; apex obtuse; base cuneate, tapering to a 1.0–1.5 mm long claw. Stamens 4–6; median filaments 2–4, 2.0–2.6 mm long; lateral filaments 2, 1.6–2.2 mm long; anthers 0.5–0.6 mm long, cream to pale yellow, when dehiscent held at a similar height to or slightly below the stigma. Ovary 2.6–2.9 mm long, 0.4–0.6 mm diam., ± terete, green, glabrous; ovules 20–20; style c. 0.2 mm long, ± terete; stigma 0.4–0.5 mm diam., white. Siliques 18.0–25.0 × 1.0–1.2 mm, glabrous, style 0.2–0.4 mm long; valves green at maturity and when dehiscent; replum 0.4–0.5 mm wide. Seeds 0.9–1.2 mm long, 0.5–0.7 mm wide, 0.3–0.4 mm thick, oblong to broadly oblong, henna; wing absent.

Cardamine sinuatifolia is distinguished by usually simple leaves, although occasionally they have 1–2 lateral pinnae, light green colour, margin with inconspicuous hydathodes, and purple-red petiole bases and stems. A notable feature of the terminal leaflets is their irregular shape, a tendency to be elliptic or oblong, and the weakly sinuate margin.

Cardamine sinuatifolia prefers to grow in damp sites such as lake margins and stream banks.​​

Flowering January–December; Fruiting January–March.