Overview
French’s Greenhood (Pterostylis frenchii) is an attractive and robust terrestrial greenhood orchid native to the coastal sandplains and tuart forests of southwestern Western Australia. Characterized by its tall flowering stem bearing a loose spike of translucent green-and-white striped flowers highlighted by reddish-brown lateral sepals, this winter-to-spring flowering species is an elegant representative of the banded greenhood complex.
Biology and Physical Characteristics
Pterostylis frenchii develops a distinct basal rosette of three to five broad, dark green leaves on non-flowering plants, whereas mature flowering plants produce smaller stem-clasping leaves along the scape. The flowering stem reaches up to 45 centimeters in height, bearing two to eight erect flowers. The dorsal sepal and petals form a prominent, arching greenhood (galea) marked with crisp white and emerald green longitudinal bands. The lateral sepals are erect, tapering into long, slender free points that flank the hood. The labellum is hidden inside, sensitive and irritable with a hairy basal appendage.
Behavior and Ecology
Flowering from July through October, Pterostylis frenchii relies on an intricate mechanical trap mechanism for pollination. When small male fungus gnats are lured inside the hood by deceptive olfactory attractants, their touch triggers the sensitive labellum to spring forward against the column wings, temporarily sealing the insect inside a biological chamber. To escape, the gnat must crawl upward through a narrow passageway past the reproductive organs, transferring pollinia in the process.
Conservation and Human Impact
Ranked as Least Concern due to extensive populations in conservation reserves, Pterostylis frenchii remains common throughout protected coastal reserves such as Yalgorup and Tuart Forest National Parks. Localized impacts include urban development along the Swan Coastal Plain, weed competition from arum lily and veldt grass, and topsoil disturbance by feral rabbits. Protecting contiguous coastal corridors preserves the insect pollinators vital to its life cycle.
Interesting Factoid
Named in honor of Charles French, an early Australian government entomologist and naturalist, this greenhood features lateral sepals with long thread-like tips that project high above the hooded flower like antennas.
Last updated: October 2026