For many years, tansy (Tanacetum vulgare) was used as a medicinal herb despite its toxicity. A bitter tea made with tansy flowers has been used for centuries as an anthelmintic to treat parasitic worm infestations, and tansy cakes were traditionally eaten during Lent because it was believed that eating fish during Lent caused intestinal worms. However, it has no place in modern herbal medicine.
Common knapweed (Centaurea nigra) is a species of flowering plant in the daisy family known by various other names e.g. lesser knapweed, black knapweed and hardheads.
Knapweed is a good source of nectar attracting bees and butterflies. Its seeds also provide food for many birds.
