Cardamine dilatata Heenan

Perennial herb, single rosette or with short lateral branches. Leaves up to 115 mm long, usually simple or irregularly pinnatifid; lamina 14.0–33.0 × 4.0–11.5 mm, grey to grey-green, coriaceous, glabrous; petiole up to 90 mm long. Terminal pinna 14.0–20.0 × 4.0–11.5 mm, simple, elliptic, broadly elliptic to obovate; margin entire, without hydathodes; apex obtuse with a ± distinct hydathode; base cuneate to attenuate. Lateral lobes 1–2, basal, 0.5–3.0 × 1.5–3.5 mm, broadly triangular to broadly elliptic; apex obtuse. Cauline leaves similar to rosette leaves but smaller, narrower, base attenuate. Inflorescence racemose, often with lateral racemes, each raceme 6–20-flowered; peduncle up to 140 mm long, 1.2–1.3 mm diam. at base, ascending, glabrous. Pedicels 15.0–26.0 mm long, 0.4–0.6 mm diam., ascending or divaricate, glabrous. Sepals 2.5–3.0 × 1.4–1.8 mm, broadly elliptic, saccate, green, glabrous, margin white and membranous, apex obtuse, base truncate. Petals 9.5–11.0 × 3.8–5.0 mm, white, limb obovate; apex obtuse; base attenuate, tapering to a c. 0.2 mm long claw. Stamens 6, dilated in lower half, 0.35–0.65 mm wide; median filaments 4, 3.6–4.4 mm long; lateral filaments 2, 2.3–2.9 mm long; anthers 0.7–0.8 mm long, maroon, when dehiscent held slightly below the stigma. Ovary 2.5–4.0 mm long, 0.5–0.6 mm diam., ± terete, green, glabrous; ovules 36–40; style 0.9–1.0 mm long, ± terete; stigma 0.3–0.4 mm diam. Siliques 21.0–29.0 × 0.9–1.1 mm, glabrous, style 1.0–1.2 mm long; valves green when developing. Seeds not seen.

Cardamine dilatata is distinguished from C. bilobata by its mostly simple to irregularly lobed grey to grey-green leaves, filaments conspicuously dilated at the base, and the silique with a short style.

Cardamine dilatata is known from two collections at the type locality in the Pareora River gorge, South Canterbury, and a subpopulation of 11 plants at Macraes, North Otago. At Pareora it was growing on a narrow, moss-covered ledge on a shaded, south-facing mudstone bluff beside the Pareora River, and at Macraes it was growing on the lower parts of large, south-facing schist bluffs that do not receive direct sunshine.

Flowering December; Fruiting December.