Flora of New Zealand Series

Acianthus rivularis A. Cunn. in Compan. bot.  Mag.  2,  1837, 376.

Nematoceras rivularis (A. Cunn.) Hook. f. Fl. N.Z.  1,  1853,  251.

Corysanthes rivularis (A. Cunn.) Hook. f. Handbk N.Z.  Fl.  1864,  266.

Type locality: "Growing among moss upon rocks in the bed of a briskly running rivulet, flowing through a deep shaded ravine near Wangaroa, Nov. 1826, A. Cunningham. 1833, R. Cunningham." Type: ?

Plant at fl. to 6 cm. tall. Stem erect. Green lf to c. 4–(5) × 3 cm., often smaller, sessile, long-ovate, acuminate, cordate at base, membr., ± blotched with red, margins ± undulate. Floral bract > ovary, acuminate. Dorsal sepal to 4 cm. long, much longer than labellum, erect then almost horizontal, gradually tapering to filiform tip; lateral sepals long, filiform, greatly exceeding labellum. Petals similar to lateral sepals. Labellum auriculate at base, lamina abruptly deflexed, squarish when flattened, contracting suddenly into a narrow apiculus, margins inclined to fold downwards, finely denticulate or erose, the denticulations ornamented with short, stiff, blunt hairs; similar hairs or hair-like calli covering the inner face of the lamina and becoming more acute and retrorse towards the throat.

DIST.: N., S., St., A.

Endemic.

Forest floor.

FL. 9–11.