This rhizomatous perennial herb occurs in damp dune-slacks and on adjacent low dunes, and in Somerset in a damp sandy hollow on a coastal golf course. Elsewhere, it occurs as an alien, especially in industrial areas. Substantial ripening of fruit and seed set appear to occur only after a long, hot summer. Lowland. The distribution of this species is stable, though native populations are at risk from scrub encroachment, which requires careful management, and hydrological changes. This plant is useful. How to get rid of: Cut back in early spring.