The Orpheum frutescens flower has a very special relationship with the female Carpenter Bee. The flower keeps its pollen from any visiting insects, but releases only to the female Carpenter Bee!
Why? There is a possibility that an insect would pick up pollen from the flower then fly to another species and fail to fertilise which in turn leads to wasted pollen.
The solution?  Simple; when the female bee approaches the flower, the bee adjusts the rate at which it beats its wings. The ‘buzz’ hits MIDDLE C and the flower releases the pollen!!
Coincidence? Who knows, but absolutely fascinating all the same.