A revision of Bryum bornholmense Wink. & R. Ruthe

Abstract Bryum bornholmense has hitherto been defined too broadly, and many plants that have been identified as this species since the taxonomy of the Bryum erythrocarpum complex was revised in 1964 are actually referable to B. rubens. B. bornholmense is most reliably distinguished from B. rubens by the maximum size, colour and position of its tubers, and the size and shape of the tuber cells. The revised distribution of B. bornholmense in the British Isles is mapped, and confirmed specimens from mainland Europe are cited. B. bornholmense is a strict calcifuge, occurring on open ground in heathland, woodland or by water, but apparently absent from arable fields. It occasionally produces synoecious inflorescences and appears to fruit more freely than most members of the B. erythocarpum complex.