Taisha launches the new year with a series on plant mimicry and deception. She writes:
Plant mimicry is described by Barrett in Mimimcry in Plants (PDF, 1987) as a three part system consisting of:
- a model — the animal, plant, or substrate being imitated
- a mimic — the organism imitating the model
- a dupe or signal receiver — the organism that cannot distinguish between model and mimic
Barrett further explains that mimicry in plants is not an active strategy, but rather arises from evolution through the occurrence of random mutations and natural selection. Also, it’s mentioned that in order for natural selection to favour the evolution of mimicry; the mimic must gain a reproductive advantage and thus increase fitness by modeling itself after an organism or substrate.
Starting this series is a member of a genus known for deceit, Ophyrus bombyliflora, or the bumblebee orchid. This photo was chosen from the Botany Photo of the Day Flickr Pool and was taken in April by Jenny (aka Crete Flowers@Flickr). Jenny photographed this flower in the village of Prodromi, located in southwest Crete, Greece. Thank you, Jenny!
The Mediterranean orchid genus Ophrys is known for its specialized pollination system of sexual deception, which is an example of Pouyannian mimicry. In Ophrys, the labellum of the flower mimics female pollinator species to attract males. The male pollinators attempt to mate with the flower (aka pseudocopulation) and pollinaria are subsequently transferred to the pollinator. Upon an attempt at copulation with a second flower of the same species, cross-pollination occurs.
Ophrys bombyliflora specifically attracts male solitary bees of the genus Eucera by chemical, visual, and tactile means, and does not seemingly offer any other pollinator rewards (e.g, nectar). It is speculated that the labellum of bumblebee orchids attracts the male Eucera bees over long distances by emitting a chemical odour from a fragrance-producing organ called an osmophore. At shorter ranges, the cuticular wax on the labellum, which is enriched with chemical attractants, seems to be the luring mechanism. It is thought that these chemical odours are similar to the pheromone of the female bees, constituting a highly specific pollinator-attracting stimulus. The compounds capable of attracting male Eucera species and the pheromone(s) produced by Eucera females remain unknown, though.
Physically, the labellum with its specific colour patterning, reflectivity, and shape is also believed to provide short-range attraction to pollinators. In addition, the shape of the labellum and specific arrangement of the stiff trichomes presents a tactile stimulus, and also ensures the bees assume the correct position for pollination. The combination of these chemical and physical traits serves as an effective deception, ensuring the necessary pseudocopulation for cross-pollination (also see: Francisco, A., Ascensão. L. 2013. Structure of the osmophore and labellum micromorphology in the sexually deceptive orchids Ophrys bombyliflora and Ophrys tenthredinifera (Orchidaceae). International Journal of Plant Sciences. 174(4): 619-636 doi:10.1086/669911 ).