Overview
The Bird Orchid (Pterostylis turfosa) is an intriguing and common terrestrial orchid native to the open jarrah forests and sandy heaths of south-western Australia. Famed for its translucent green and reddish-brown striped galea and exceptionally long, thread-like lateral sepals that curve gracefully downward like the tail streamers of a diving bird, it is one of the most distinctive greenhood orchids in the Western Australian bush.
Biology and Physical Characteristics
Pterostylis turfosa produces a basal rosette of three to six ovate, dark green leaves that wither as the flowering stem reaches maturity. The slender stem carries a solitary, semi-erect flower dominated by a curved, translucent hood (galea) boldly striped with olive-green and reddish-brown. The lateral sepals are united at the base and terminate in extraordinarily long, filiform tips that sweep downwards, while the labellum is narrow, curved, and equipped with a sensitive irritable hinge.
Behavior and Ecology
Flowering from September to November, Pterostylis turfosa utilizes a rapid touch-sensitive pollination trapdoor mechanism. Attracted by alluring floral scents mimicking fungus gnat pheromones, male gnats alight on the exposed labellum. The sudden displacement of the insect triggers the labellum to snap sharply upward into the hooded galea, imprisoning the gnat. In its attempt to climb out through the only illuminated exit at the top of the column, the gnat collects or deposits pollinia, achieving cross-pollination before the labellum resets after several minutes.
Conservation and Human Impact
Pterostylis turfosa is evaluated as Least Concern, widely protected in numerous national parks and nature reserves including Porongurup, Stirling Range, and Shannon National Parks. Main conservation considerations involve preventing excessive recreational soil compaction, managing controlled fuel reduction burns outside the active winter-spring growing cycle, and safeguarding mossy granite margins.
Interesting Factoid
The common name ‘Bird Orchid’ refers to the unique profile of the flower, whose sweeping lateral sepal filaments and curved hood create the uncanny appearance of a diving waterbird or bird in flight.
Last updated: October 2026