Lindsay is the author of today's entry:
An opportunistic terrestrial species of eastern Australia, the pink fingers orchid thrives in open, seasonally wet areas. Despite its small size--it only grows to about 20mm--the pink finger orchid emits a strong musky scent. This orchid has evolved to mimic the pheromones of the female thynnid wasp. It attracts male wasps by mimicking the smell and shape of the flightless female, who become the unwitting pollinator of this species.
The sexual life of the orchid family is characterized by its very specialized pollination systems and it is estimated that one third of the 30 000 or so accepted species use deception to attract pollinators. In the case of Caladenia carnea, it is a sexual deception--an adaptation unknown outside the Orchidaceae.
There is an ongoing discussion among biologists and evolutionists as to how, exactly, deception increases the overall fitness of a species. A number of explanations have been suggested, including: 1) the amount of pollen typically produced by orchids is so little that one visit from a pollinator is enough to effectively remove the pollen or pollinate the non-rewarding flower; and 2) that deception promotes cross-pollination, which would explain the high level of hybridization, and consequently adaptation, in the orchid family. These hypotheses are not without their problems, however, and the sexual life of orchids is still the subject of heated debate.