A perennial herb of calcareous mires, marshy grassland, water-meadows, flushes, Salix fen-carr and Alnus woods. 0-780 m (Cross Fell, Cumberland).
A perennial herb found in a wide range of habitats. Subsp. sambucifolia occurs in damp grassland, marshes, fens, water margins and ditches, and wet woods throughout the country; subsp. collina in dry calcareous grasslands, hedge banks and woodland rides in S. and C. Britain. Lowland to 805 m on Mt Brandon (S. Kerry).
A perennial herb, naturalised in damp woods and shady hedge banks. Generally lowland, but reaching 305 m near Bridgend, Dufftown (Banffs.).