Pterostylis russellii, commonly known as Russell's greenhood, is a species of orchid endemic to eastern Australia. Non-flowering plants have a rosette of leaves flat on the ground but flowering plants have a single shiny white and dark green flower on a flowering stem lacking a rosette but with a few spreading stem leaves.
Pterostylis russellii is a terrestrial, perennial, deciduous, herb with an underground tuber and when not flowering, a rosette of between three and six dark green, oblong to heart-shaped leaves, each leaf NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide. Flowering plants have a single shiny dark green and white flower NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide on a stem NaNsigfig=1NaNsigfig=1 tall with three to five stem leaves. The dorsal sepal and petals are fused, forming a hood or "galea" over the column curving forward in a semi-circle. The dorsal sepal ends with a thread-like tip NaNsigfig=1NaNsigfig=1 long. The lateral sepals are held closely against the galea, have erect thread-like tips NaNsigfig=1NaNsigfig=1 long and a protruding, V-shaped sinus between their bases. The labellum is about NaNsigfig=1NaNsigfig=1 long and about 3sigfig=1NaNsigfig=1 wide, blackish, blunt and protruding above the sinus. Flowering occurs from April to August.[1] [2]
Pterostylis russellii was first formally described in 1952 by Trevor Hunt from a specimen collected near Brisbane and the description was published in The Orchid Journal (California).[3] The specific epithet (russellii) honours "Mr. A.J. Russell, then Captain Russell, a keen and competent student of Australian orchids" who first collected this species.[4]
Russell's greenhood grows in moist, shady places in forest between Grafton in New South Wales and Gympie in Queensland.