Pterostylis australis

Detailed description

Terrestrial, tuberous, glabrous, spring to summer-green perennial herb forming large colonies through vegetative extension. Plant at flowering 100–250 mm tall. Stem erect, smooth, dark green to reddish green, internodes < leaves. Leaves 4–5, shape changing from base to top of stem; lamina 40–150 × 10–16 mm, dark green to yellow-green, the lowest and those of non-flowering plants, elliptic to broadly elliptic, apex subacute, base subsessile or with a reddish-green winged petiole, margins entire or sometimes finely toothed; mid-stem and upper leaves longer and slightly narrower, more tapered, rarely narrowly lanceolate, margins entire or finely denticulate, 1, 2 or none of the leaves overtopping the flower. Flower solitary, large, dark green to pale green striped with white. Ovary erect. Dorsal sepal 25–45 mm tall, often rather smoothly arcuate but sometimes erect below then sharply horizontal above, apex acuminate often shortly caudate; lateral sepals diverging at a narrow angle, apices strongly reflexed backwards, spreading. Petals shorter than dorsal sepal, acute or acuminate. Labellum basally dark green flushed red or red from mid-section to apex, apex distinctly darker; lamina lanceolate-oblong, slightly arched, broadened almost to middle then narrowing to an obtuse, more or less deflexed, and decurved, pinched tip. Column as tall as labellum; stigma linear, often as broad as column, sometimes overlapped by wings from above.