early donkey orchid

Diuris perialla is a tuberous, perennial herb with two or three linear to lance-shaped, bright green leaves 50–200 mm (2.0–7.9 in) long and 3–7 mm (0.12–0.28 in) wide. Up to four yellow flowers with reddish markings, 25–40 mm (0.98–1.57 in) long and 20–30 mm (0.79–1.18 in) wide are borne on a flowering stem 150–350 mm (5.9–13.8 in) tall. The dorsal sepal is egg-shaped, 8–10 mm (0.31–0.39 in) long and 3–4 mm (0.12–0.16 in) wide, the lateral sepals narrowly oblong, down-turned and crossed with curved tips, 13–20 mm (0.51–0.79 in) long and 3.0–3.5 mm (0.12–0.14 in) wide. The petals are elliptic, 12–14 mm (0.47–0.55 in) long and 8–10 mm (0.31–0.39 in) wide on a stalk 3–6 mm (0.12–0.24 in) long. The labellum is 6–9 mm (0.24–0.35 in) long with three lobes - the centre lobe broadly wedge-shaped, 6–8 mm (0.24–0.31 in) long and 8–9 mm (0.31–0.35 in) wide, the side lobes spread widely apart and oblong to egg-shaped, 8–10 mm (0.31–0.39 in) long and 4–6 mm (0.16–0.24 in) wide. There is a single smooth, yellow callus ridge 4–5 mm (0.16–0.20 in) long, along the mid-line of the labellum. Flowering occurs from late May to Mid July.

Early donkey orchid grows in low, shrubby heathland on laterite breakaways, in the area between Regans Ford, Mogumber, Northampton and Mingenew in the Avon Wheatbelt, Geraldton Sandplains, Jarrah Forest and Swan Coastal Plain bioregions of south-western Western Australia.