Warnstorfia exannulata, an aquatic moss in the Arctic: seasonal growth responses

Abstract

The moss, Warnstorfia exannulata (Schimp.) Loeske, was first reported forming a carpet beside a water pool in Ny-Alesund (78°56′N), Svalbard in 1959. Fifty years later, in 2008, it was found growing as an aquatic in a pool. The moss is sensitive to seasonal changes and exhibits a pattern of seasonal growth: summer stems with densely arranged leaves and lateral branches, and winter growth with short-leaved stems and no lateral branch. The mean daily increase in stem length is 0.68 mm in summer and 0.07 mm in winter. The longest specimens were up to 8 years old. The growth of the moss reflects closely seasonal temperature and growth conditions. World distribution is discussed and global distribution mapped.