Nectar
What the insects really want is the plants' nectar, a sugary liquid which is an important source of energy for the visiting insects. Why nectar? It is precisely in order to attract insects so that they can assist with the pollination process.
Sticky pollen
When the flies move about on a plant´s flower blossom, pollen fastens to their bodies because the pollen is often sticky. When the flies move on, some of the pollen they transport fastens to the next flower, which can then be fertilized.
Wolf's-bane
The flowers look like hats, with the nectar located furthest up on the inside. Purple wolfs-bane is often visited by bumblebees, which have long tongues. They crawl deep inside the blossom and stretch their tongues upward to reach the nectar.
Plant's dilemma
The longer the visitor's tongue, the deeper in the flower the nectar has to be placed. This is because the flower must get the bumblebee to crawl in sufficiently deep that some pollen is certain to rub off on its body. Otherwise, pollination will not take place.
