Cornflower? Why would they call it a cornflower?
That is a typical American reaction to the English name for a bachelor button, Centaurea cyanus.
The story is this:
Bachelor buttons, the plants in the photos, are native to Europe. For all but the last 100 or 150 years, grain crops like wheat and oats were planted by people walking the fields scattering seeds, weeded by farm workers with hoes and harvested by a crew cutting the grain with sickles.
In those fields in Europe, bachelor buttons grew abundantly.
The general word for grain crops--wheat, oats, rye, barley--in Great Britain was "corn."
When English speakers reached the Americas and saw a new grain, they called it "Indian corn." Americans have long since dropped the "American" and so the American grain Zea mays is "corn." But that is a relatively new use of the word corn.
Corn flowers were flowers that grew in the corn. The pretty blue bachelor buttons.
People turned cornflowers into garden flowers easily 400 years ago, so there are pink, purple and white ones as well as blue.
Blue remains the characteristic color, and "cornflower blue" is a recognizeable shade.
The name Centaurea is based on a Greek myth in which the centaur Chiron, wounded by a poison arrow from the nine-headed hydra, healed himself using cornflowers on the wound. The catch is that the myth confuses two plants: cornflowers have no medicinal value. (Except perhaps as a tonic. Certainly not against poison.) It is believed that the plant in the myth was a gentain, centuary (Centaurium). The incorrect identification of the healing herb goes back to Theophrastus, 288 B.C.
Cyanus is a Greek word for dark blue. I found two quite different associated stories, first that Cyanus was mythological youth who loved the flowers, spent all his time making wreaths of them and died on a bed of cornflowers, so the goddess Flora named the flower after him. Alternatively, they are named for the nymph Cyane who, when Persephone was abducted by Hades, was so distraught she turned herself into a deep blue pool.Once a common crop weed, cornflowers are now considered at risk of extinction in northern Europe. They have escaped from cultivation in places, but wild cornflowers have become exceedingly rare. The explanation seems to be changes in agricuture. Mechanical seeding and harvesting replaced hand seeding and harvesting, and the seeds were better screened to exclude weed seeds. But probably more important was the use of herbicides on the fields after the Second World War.
The name bachelor button also has several possible origins. First, the Oxford English dictionary says a number of double round flowers were called bachelor buttons, but none of the examples given in the OED are blue or a Centaurea. Second, if you Google "bachelor button," you can find a button that does not need sewing. Some are round and somewhat like the flower (link). Third, there is also a story that the bachelor put a bachelor button flower in his lapel when he decided to go courting.
In southern Europe wild cornflowers are not considered endangered, and of course millions are planted as garden flowers every year, all over the world.
And yet, from a common weed to a rare species in about 100 years...!
It makes you stop to think about how many ways daily life has changed in that century--mechanized agriculture, supermarkets and international trade in food, plastics of all sorts, electricity, freezers, and microwave ovens--to name a few that would affect the life and times of a crop weed.
Comments and corrections welcome.
Durant, M. Who Named the Daisy? Who Named the Rose? A Roving Dictionary of North American Wild Flowers. St. Martin's Press, New York. 1983.
Eland, S. C. Plant Biographies 2013.
Martin, L. C. Garden Flower Folklore. The Globe Pequot Press, Chester CN 1987PDR (Physician's Desk Reference) for Herbal Medicine. 4th edition. Thompson Healthcare, Montvale, NJ. 2007.