The rare South African iris (Lapeirousia oreogena) has a ring of six stunning purple petals, atop an equally vivid straw-like stem. The petals have white marks, which look like arrows pointing towards the centre of the flower. And that’s exactly what they are.

The iris is pollinated by the accurately named “long-proboscid fly”, whose tongue is twice as long as its body. It hovers over the flower and aims for the centre, driving its tongue deep into the stem to reach the pool of nectar at the bottom. As it drinks, its head pushes against the flower’s male organs, which deposit a dollop of pollen. When the fly leaves, it carries this payload to another iris. The flies and the flowers