Pterostylis jacksonii

Pterostylis jacksonii is a terrestrial, perennial, deciduous, herb with an underground tuber and a compact rosette of leaves 15–35 mm (0.6–1 in) in diameter. Flowering plants have a single green and white flower 9–11 mm (0.35–0.43 in) long and 5–8 mm (0.2–0.3 in) wide on a flowering stem 40–80 mm (2–3 in) high, sometimes with a light brown tinge. There is a single stem leaf 6–8 mm (0.2–0.3 in) long and 3–4 mm (0.1–0.2 in) wide on the flowering stem. The dorsal sepal and petals are fused, forming a slightly inflated hood or "galea" over the column. The lateral sepals are held close to the galea, almost closing the front of the flower and have erect, thread-like tips 14–17 mm (0.6–0.7 in) long. The labellum is broad but not visible from outside the flower. Flowering occurs in June and July.[2]

Pterostylis jacksonii was first formally described in 2014 by David Jones and Christopher French from a specimen collected in the Mount Frankland National Park and the description was published in Australian Orchid Review. The species had previously been known as Pterostylis sp. 'granite'.[3] The specific epithet (jacksonii) honours William Pownall Jackson, who discovered this species.[3]

The southwest granite snail orchid grows with moss on granite outcrops between Walpole and Albany in the Warren biogeographic region.[2][4]

Pterostylis echinulata is classified as "not threatened" by the Western Australian Government Department of Parks and Wildlife.[4]