Blessed thistle

Centaurea benedicta (syn. Cnicus benedictus), commonly called blessed thistle or St. Benedict's thistle, is an annual herb in the Asteraceae family reaching approximately 60 cm in height. The plant displays leathery, hairy leaves up to 30 cm long and 8 cm broad, with small spines along the margins, and a light down covering on all parts. Yellow disc flowers are borne in dense flowerheads 3-4 cm in diameter, surrounded by numerous spiny pinnate bracts. The sprawling habit, hermaphroditic insect-pollinated blooms, and preference for full sun and well-drained sandy to clay soils characterize the species. Flowering occurs from May to September, and the plant is hardy to UK zone 8. Native to the Mediterranean region from Portugal east to Iran, it has naturalized widely in temperate areas as a weed of disturbed ground and is cultivated for medicinal use. The aerial parts, harvested as flowering begins, yield the bitter sesquiterpene lactone cnicin, which underlies its long-standing reputation as a digestive bitter.