Overview
The Shirt Orchid (Thelymitra campanulata), also known as the Bell-flowered Sun Orchid, is a distinctive terrestrial orchid native to the windswept coastal heaths and limestone ridges of south-western Australia. Unlike many sun orchids whose flowers open flat like stars only during intense heat, the blossoms of Thelymitra campanulata remain charmingly bell-shaped or cupped, adorned with striking dark blue longitudinal pinstripes that resemble the fabric pattern of a striped collared shirt.
Biology and Physical Characteristics
Thelymitra campanulata produces a single narrow, fleshy, channelled leaf that clasps the lower stem. From August to October, the wiry flowering stem bears an open raceme of two to ten nodding, bell-shaped flowers. The perianth segments are pale sky-blue, lilac, or milky white, prominently decorated with prominent navy or cobalt longitudinal stripes. The central column is crowned by two bright yellow lobes fringed with delicate white hair tufts, protecting the reproductive organs within the semi-closed floral cup.
Behavior and Ecology
The bell-shaped posture of Thelymitra campanulata is an adaptation to windy coastal conditions, shielding internal pollen organs from salt spray and driving coastal winds. The orchid relies on food deception (floral mimicry), displaying vibrant blue petals and a yellow column structure that mimics nectar-rich native lilies and peas. Solitary native halictid and colletid bees visit the flowers seeking nectar, inadvertently contacting the sticky viscidium and transferring pollen packets between adjacent plants.
Conservation and Human Impact
The Shirt Orchid is evaluated as Least Concern, enjoying wide distribution across numerous coastal national parks, including Kalbarri, Nambung, and Cape Le Grand National Parks. The primary ecological considerations involve mitigating trampling by off-road four-wheel-drive vehicles along coastal tracks, preventing shoreline sand dune erosion, and protecting native kwongan heath from invasive coastal weeds.
Interesting Factoid
The common name ‘Shirt Orchid’ originated among early Western Australian naturalists who noted that the crisp blue-and-white pinstriped petals looked just like the patterned fabric of men’s striped business shirts.
Last updated: October 2026