Pterostylis dubia

Pterostylis dubia, is a terrestrial, perennial, deciduous, herb with an underground tuber. It has a rosette of leaves which are 15–60 mm (0.6–2 in) long, 8–20 mm (0.3–0.8 in) wide and have a stalk. Flowering plant have a single dark green and white flower 20–26 mm (0.8–1 in) long and 9–12 mm (0.4–0.5 in) wide is borne on a flowering stem 80–200 mm (3–8 in) tall with stalkless stem leaves. The dorsal sepal and petals are joined, forming a hood called the "galea" over the column. The petals are not flared and are similar in length to the dorsal sepal which ends in a point. There is a wide gap at each side of the flower between the galea and the lateral sepals. The lateral sepals are erect and have a tapering tip, 14–22 mm (0.6–0.9 in) long, only slightly taller than the galea and there is a notch in the bulging sinus between them. The labellum is 13–17 mm (0.5–0.7 in) long, about 3 mm (0.1 in) wide, dark bluish-green, curved and protrudes prominently above the sinus. Flowering occurs from November to January.[2][3]

Pterostylis dubia was first formally described in 1810 by Robert Brown and the description was published in Prodromus Florae Novae Hollandiae et Insulae Van Diemen.[1][4] The specific epithet (dubia) is a Latin word meaning "wavering", "uncertain" or "doubtful".[5]

The blue-tongued greenhood grows in wet forest at altitudes above 500 m (1,600 ft) in central and southern Tasmania.[2][3]