Chiloglottis is a genus of approximately 25 species of terrestrial orchids in the family Orchidaceae, order Asparagales. Commonly known as wasp orchids, ant orchids, or bird orchids, the genus is native to eastern Australia and New Zealand, including the Chatham and Antipodes Islands.
Plants grow as low-growing herbs in colonies of genetically identical individuals. Each plant typically produces two leaves at ground level and a single resupinate (upside-down) flower held on a slender stem. The most distinctive feature is the labellum — a roughly diamond-shaped lip adorned with dark stalked glands called calli, which together create a convincing imitation of the body of a wingless female thynnine wasp.
Chiloglottis is renowned for its extraordinary pollination strategy: sexual deception, or pseudocopulation. Rather than offering nectar or pollen rewards, the flowers release chemical compounds from glands on the sepals that closely mimic the sex pheromones of female thynnine wasps. Male wasps are drawn by scent, land on the labellum, and attempt to mate with what they perceive to be a female. In doing so, they contact the column and either deposit or collect pollinia. Strikingly, each Chiloglottis species is pollinated by a different, specific wasp species — a textbook example of co-evolution and chemical mimicry. The exception is Chiloglottis cornuta, which is self-pollinating.
The genus was first formally described by the botanist Robert Brown in 1810, with Chiloglottis diphylla designated as the type species.
Etymology
The genus name Chiloglottis derives from the Greek cheilos (lip) and glōssa (tongue), referring to the distinctive lip (labellum) of the flower. The genus was named by Robert Brown in his landmark 1810 work Prodromus Florae Novae Hollandiae et Insulae Van Diemen.
Distribution
Chiloglottis is native to eastern Australia and New Zealand, with the range extending to the Chatham Islands and the Antipodes Islands. Within Australia the genus is largely confined to the south-eastern states, where species grow in eucalypt woodland, heath, and shrubland habitats.
Ecology
Chiloglottis species are master practitioners of sexual deception. Their flowers produce chemical signals — principally alkylpyrazines and related compounds — that closely mimic the contact sex pheromones of specific female thynnine wasps (family Thynnidae). Male wasps, emerging before females in spring, detect these wind-borne scents and attempt to mate with the labellum. The labellum's stalked calli reinforce the illusion by mimicking the wasp's body shape and texture. During the pseudocopulation attempt the wasp contacts the column, picking up or depositing pollinia. Because each orchid species produces a chemically distinct signal targeting a single wasp species, there is essentially no cross-pollination between Chiloglottis species — a precise and species-specific mutualism. Chiloglottis cornuta is the notable exception, having lost this deception mechanism and become self-pollinating.
