Alcock's Duck Orchid

Caleana alcockii has a single smooth green or red leaf, 20–30 mm (0.8–1 in) long and 5–12 mm (0.2–0.5 in) wide. Usually only one greenish-yellow and red flower, about 20 mm (0.8 in) long and 10 mm (0.4 in) wide is borne on a thin, wiry stalk 80–160 mm (3–6 in) high. The dorsal sepal, lateral sepals and petals are narrow and hang downwards with the dorsal sepal pressed against the column which has broad wings, forming a bucket-like shape. About one-third of the outer part of the labellum is covered with glossy black glands or calli and the labellum has a prominent hump at its centre. Flowering occurs from September to October.

Caleana alcockii grows with grasses or sedges in sandy soil in a small area north of the Murchison River in the Geraldton Sandplains biogeographic region.