A well known botanical phenomenon—one that I mention in WEIT—is pseudocopulation, in which orchids attract insect pollinators by modifying their labellum (one of the petals) to roughly resemble a bee or a wasp. Short-sighted male insects mistake the labellum for a female, land on it, and try to copulate. Their efforts are of course fruitless, but this is the way the orchid gets itself pollinated. During the act, the insect dislodges the pollinia (a mass of pollen grains stuck together) from the orchid, which sticks to its body, ready to pollinate the next orchid on which it lands (insects apparently have short memories).
There are of course many cases in which insects have evolved to resemble plants to hide themselves from either predators or prey. Insect-mimicking orchids are more or less the reverse, with the plant using the insect as a kind of flying sex organ. Sometimes, in a form of deceptive chemical mimicry, natural selection has even modified the orchid’s fragrance to resemble the pollinator’s pheromones. Click on the link in the second line to see more examples of pseudocopulation.
Here’s the Australian orchid Chilglottis formicifera, pollinated by pseudocopulating wasps.
Here’s Ophrys speculum, a wasp mimic, and an Attenborough video of a randy bee attempting copulation with that orchid but achieving pollination:
Often the flower’s mimicry is so precise that you can guess the pollinator. I saw this flower yesterday, which stumped me at first:
But then I realized that it’s probably pollinated by this: