The edible carrot was spread by the Romans throughout their empire, and probably reached our shores with the coming of the Normans. But the wild progenitor of this crop grows all around our shores, and has probably done so for millennia. The tough tap-root of this wild relative smells strongly of carrot, but is tough and inedible. In August its cow-parsley-like flowers are in full bloom, not just on grassy sea-shores, but on many of our inland motorway verges too. The botanical family to which it belongs the umbellifers all share the umbrella-like flower heads.
But the little white saucers of flowers are not all the same. Take a look and you will see that about one in five has a vivid purple dot at its centre. This is a clever innovation to improve the pollination of its flowers. Like hogweed, cow-parsley and even the elder tree, these flat white inflorescences are mostly pollinated by flies. The wild carrot is exploiting a simple bit of fly behaviour known as the fly-paper effect.
The old-fashioned sticky fly-paper takes a long time to catch its first fly more by accident that allure. However, once one fly is caught, the paper suddenly becomes a lot more attractive to other passing flies. Like miniature vultures, they suspect any dark dot indicates another fly, possibly enjoying a feast, and land nearby. As more flies are caught so the appeal of the paper increases exponentially. The carrot is laying down a decoy fly to speed up the first arrival. But nor are these flies disappointed, the flowers do indeed offer, an admittedly small, reward of nectar.
So, why don't all the flowers have the central droplet of purple? I'm delighted to say that is a complete mystery!