Definition of "ragwort"

Ragwort is under the command of dame Venus, and cleanses, digests and discusses.

1653, Nicholas Culpeper, The English Physician Enlarged, Folio Society, published 2007, page 237

Sea-poppies and ragwort were plants of ill-fame, too.

1936, Rollo Ahmed, The Black Art, London: Long, page 157

As we all know, witches ride through the air on a broom, but sometimes their means of locomotion was a bulrush, a branch of thorn, mullein stalks, cornstalk, or ragweed, called fairies' horse in Ireland.

1940, Rosetta E. Clarkson, Green Enchantments: The Magic Spell of Gardens, The Macmillan Company, page 267