Orchids Do It Differently

Most flowers discretely dust their pollen on visiting insects, but orchids go the whole hog and glue their entire stamens to their visitors. The paired stamens – known as pollinia in orchids - sit inside the hooded upper petal (top photograph) and the nectar supply is hidden deep within the flower, so even long-tongued bees like the one in the second photograph must force their head in to reach it. And that’s when they make contact with the base of the pollinia, which become glued to their head, so when the bee leaves it carries the pollinia with it. By the time it’s reached the next plant each pollinium has split open, exposing pollen that’s dusted on to the stigma of the receiving plant. You can see the white, ruptured pollinia just below the antenna on the face of the bee in the third picture, and the same area enlarged on the final image. Bees are often irritated by having these objects glued to their head and sometimes try to comb them off, but seldom succeed. Why do orchids operate in this way? Well each individual orchid flower can produce hundreds – sometimes thousands – of ovules and it needs a comparable number of pollen grains to ensure that they’ll all be fertilised and develop into seeds – despatching a whole stamen’s worth of pollen in one go, glued to an insect, does the trick very nicely.