whose distribution is confined to Scotland, although recent research suggests that it may be a variant of C. fragilis rather than a species in its own right. Non-vascular plants Scotland provides ideal growing conditions for many bryophyte species, due to the damp climate, absence of lengthy droughts and winters without protracted hard frosts. In addition, the country's diverse geology, numerous exposed rocky crags and screes and deep, damp ravines coupled with a relatively pollution-free atmosphere enables a diversity of species to exist. This unique assemblage is in marked contrast to the relative impoverishment of the native vascular plants. There are about 920 species of moss and liverwort in Scotland, with 87% of UK and 60% of European bryophytes represented. Scotland's bryophyte flora is globally important and this small country may host as many as 5% of the world's species (in 0.05% of the Earth's land area, similar in size to South Carolina or Assam). The mountains of the North-west Highlands host a unique bryophyte community called the "Northern Hepatic Mat", which is dominated by a variety of rare liverworts, such as Pleurozia purpurea and Anastrophyllum alpinum. Scotland has played an important part in the development of the understanding of bryology, with pioneers such as Archibald Menzies and Sir William Hooker commencing explorations at the end of the eighteenth century. Tetrodontium brownianum is named after Robert Brown who first discovered the plant growing at Roslin near Edinburgh and several other species such as Plagiochila atlantica and Anastrepta orcadensis were also first discovered in the country. Mosses Sphagnum is common and harvested commercially for use in hanging baskets and wreaths and for medical purposes. Glittering Wood-moss, Woolly Hair-moss (Racomitrium lanuginosum) and Bristly Haircap (Polytrichum piliferum) are amongst many other abundant natives. Endemic species include the Scottish Thread-moss, Dixon's Thread Moss and Scottish Beard-moss. In the Cairngorms there are small stands of Snow Brook-moss and Alpine Thyme-moss, and an abundance of Icy Rock-moss, the latter's UK population being found only here and at one site in England. The west coast is rich in oceanic mosses such as Cyclodictyon laetevirens and the Ben Lawers range also provides habitats for various rare species such as Tongue-leaved Gland Moss. Perthshire Beard-moss is a European endemic, occurring at only four European sites outside Scotland and it is classified as "Critically Endangered". Liverworts and hornworts There are numerous common liverworts such as Conocephalum conicum and Marchantia polymorpha. Autumn