Carduus is a genus of flowering plants in the aster family, Asteraceae, and the tribe Cynareae, one of two genera considered to be true thistles.
Alpine thistle not only tolerates lime-rich soils, it prefers to thrive in them. The soil should be moderately nutrient-rich, deep and very permeable – a secure drainage of water is pretty much the only thing that the undemanding perennial cannot do without.