Overview
The Crab-lipped Spider Orchid (Caladenia plicata) is a charming and architecturally curious terrestrial orchid endemic to the high-rainfall forests of southwestern Australia. Distinguished by its uniquely folded, crab-like labellum with prominent purplish-red comb teeth and dark glandular clubs on the dorsal sepal, this diminutive spider orchid is an emblem of the lush jarrah and karri forest understories.
Biology and Physical Characteristics
Caladenia plicata features a solitary hairy basal leaf measuring 4 to 8 inches in length. In spring (September to November), a slender, pubescent stem emerges bearing one to two fragrant blossoms. The perianth segments are pale yellowish-green with dark reddish central lines. The defining floral feature is the labellum: broadly ovate, folded laterally into a crab-like profile, with fringe-like lateral teeth and rows of deep red calli along the central channel.
Behavior and Ecology
Like many Western Australian Caladenia species, pollination is mediated exclusively through sexual deception of male thynnid wasps. Osmophores located on the clubbed dorsal sepal emit volatile semiochemicals that mirror female thynnid pheromones. Intoxicated male wasps attempting copulation with the labellum are tipped against the column, successfully picking up or depositing sticky pollinia before releasing the flower.
Conservation and Human Impact
Evaluated as Least Concern, the Crab-lipped Spider Orchid is widely distributed and securely conserved within Warren National Park, Walpole-Nornalup National Park, and Shannon National Park. Key management priorities include maintaining natural low-intensity fire regimes, preventing root damage by feral pigs, and protecting mature jarrah-marri canopy cover from clear-felling.
Interesting Factoid
The common name ‘Crab-lipped Spider Orchid’ references the distinctive sideways folded shape of the flower’s labellum, which bears an uncanny resemblance to the tucked carapace and legs of a small shore crab.
Last updated: October 2026