About Pterostylis oliveri Petrie
Pterostylis oliveri Petrie is a terrestrial, perennial, deciduous herb that grows from an underground tuber. Flowering individuals produce between three and five spreading leaves, which measure 50–100 mm (2–4 in) long and 20–30 mm (0.8–1 in) wide. The leaves change shape from narrow egg-shaped near the plant's base to lance-shaped near the top. A single green and white flower grows on a flowering stem that is 100–380 mm (4–10 in) tall. The dorsal sepal and petals are fused together to form a hood, called a "galea", that covers the column. The dorsal sepal is 30–50 mm (1.2–2.0 in) tall, it curves forward then bends strongly downward, and ends in a long tapering tip that is much longer than the petals. A gap sits between the galea and the lateral sepals; the lateral sepals have long tapering tips, spread apart from each other, and are either erect or turned back behind the galea. The labellum is gently curved and protrudes above the sinus between the lateral sepals. This species flowers in December and January. Oliver's greenhood grows in forest and scrub, most often beside streams or in dense leaf litter. It occurs on New Zealand's South Island, ranging from near Nelson to Arthurs Pass National Park.
