Marsh Woundwort (Photo: Laurie Campbell)
This flower smells great to bees and other insects, like flies. But the marsh woundwort plant only wants bees to get at the pollen. So it has a clever system to stop unwelcome flies - the entrance to the flower is guarded by a ring of hairs that only allows bees to get to the pollen.
This plant has been used to heal wounds for 500 years, and is still used in modern herbal medicines.
by Alison Tyler