It was the centaurea, represented here by the blue Ragged Sailor of gardens, and not our Centaury, a distinctly American group of plants, which, Ovid tells us, cured a wound in the foot of the Centaur Chiron, made by an arrow hurled by Hercules.
"Wild Flowers Worth Knowing"
Neltje Blanchan et al
Black Knapweed, the centaurea nigra, is a common tough-stemmed composite weed growing in our meadows and cornfields, being well known by its heads of dull purple flowers, with brown, or almost black scales of the outer floral encasement.
"Herbal Simples Approved for Modern Uses of Cure"
William Thomas Fernie
The following sections are on centaurea, solsequium, celidonia, pipernella, materfemia, mortagon, pervinca, rosa, lilium, egrimonye.
"The Old English Herbals"
Eleanour Sinclair Rohde