Eryri is the most southerly mountain range in Britain with summits of over 914 metres (3,000 feet). As a consequence, it is also the southern-most station for a number of Britain's montane vegetation communities, and also a range of arctic alpine plants. The importance of the montane vegetation in this area has been recognised both nationally through the notification of the three highest mountain ranges as the Eryri Site of Special Interest (SSSI), but also internationally through the designation of this site as the Eryri/Snowdonia Special Area of Conservation (SAC). In addition many of the upland habitats that are present are listed in the UK Biodiversity Action Plan (BAP). One of the arctic alpine plants which characterises some of Eryri's most exposed and inhospitable summits and crags is Salix herbacea, the smallest of the British willows. Salix herbacea is a component species of Carex bigelowii-Racomitrium lanuginosum moss-heath (National Vegetation Classification (NVC) code U10), chasmophytic vegetation of rock crevices and rocky tors, and very rarely a component of flush/spring vegetation including (NVC code M3I) Anthelia julacea-Sphagnum auriculatum spring. The habitat that supports the largest stands of S. herbacea is the moss-heath and this occupies plateaux and ridges from 730-970 metres. Less frequently, it also occurs as a component of chasmophytic communities, usually with very few individuals at each site, and with an altitudinal range of 670 -998 metres. This dataset is a collation of the results from a survey of the distribution of stands of Salix herbacea on the Glydeiriau, and comparisons between this data-set, and a similar data-set of 1986. The purpose of this data capture was to: - Assess the condition of those plant communities which support Salix herbacea and where these communities are found to be in unfavourable condition, - Assess the causes and impacts that have lead to this condition; - Identify any changes in distribution that may have occurred during the period between the capture of data sets in 1986 and 2007 and which might be attributed to climate change; - Identify those stands of vegetation which might be expected to be most vulnerable to climate change, and which might be monitored in future years. All suitable habitat on the Glydeiriau above 600 metres which supported Salix herbacea, included H6150: Siliceous alpine and boreal grasslands on summits, summit ridges, and bwlchs. H8220: Siliceous rocky slopes with chasmophytic vegetation, particularly on exposed ridges and bwlchs, and high level.