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libutron:

The Large Flying Duck Orchid: a sexually deceptive orchid

This is a beautiful shot of the Large Flying Duck Orchid, Caleana major (Asparagales – Orchidaceae), an Australian species which can be found from Queensland to South Australia, and even Tasmania.

As many other orchid species, Caleana major is a sexually deceptive orchid, adapted to attract specific male insects that are fooled into attempting to mate with orchid flowers and inadvertently acting as pollinators. This species is pollinated by sexually-attracted male sawflies.

The ‘upside-down’ flower of Caleana major is reddish-brown, 15-20 mm long. The labellum or tongue, at the top, is a deep red and attached to the rest of the flower by a sensitive strap. When the insect touches the sensitive labellum it snaps shut, trapping the insect in the sticky body of the column. It deposits pollen it may be carrying and picks up more. It is then released to fly to the next orchid.

Deception involving orchid mimicry of insect scent signals is becoming well understood for some species. Several recent discoveries indicate that the most important attractants are floral scents that mimic species-specific female-insect sex pheromones. However, visual and tactile signals such as color, shape, and texture remain neglected. 

References: [1] – [2] – [3] – [4]

Photo credit: ©Kris Kopicki | Locality: Freycinet National Park, Tasmania (2009)