Usnea fragilescens Lynge

Kyststry

World distribution: According to Clerc (1987), Usnea fragilescens agg. belongs to the eu-oceanic element in the European flora in the sense of Degelius (1935). The species also occurs rarely in the Mediterranean area. Usnea fragilescens s. str. has the most restricted distribution, being known only from France, westernmost (and rarely eastern) British Isles, and Norway. Thus in northwest Europe that species shows largely a western British Isles to western Norway disjunct distribution. In Fennoscandia the species complex is restricted to Norway

Ecology: Results. The aggregate has been collected on bark of Pinus sylvestris (14), moss covered cliffs (14), Betula sp. (2), and on bark of Alnus glutinosa (1), and Populus tremula (1). The habitats included Pinus forests (9 sites), more rarely open coastal heaths, and Quercus and Betula forests. On the tree trunks, the aggregate was most abundant on the shaded side of the trunks. Some records were from exposed, coastal rock. Recorded aspects were northern and northeastern, occasionally western. Discussion. Usnea fragilescens agg. grows on bark of Pinus sylvestris, more rarely on other trees, and on moss covered rock walls. The aggregate seems to be corticolous more frequently than saxicolous; saxicolous thalli grow on exposed as well as on sheltered cliffs (see also Clerc 1987). According to Clerc the aggregate occurs on siliceous rather than calcareous rock. Corticolous specimens seem to be most luxurious in old woodlands

Threats: Results. Recorded threats include planting of Picea (3549, 1363), felling of substrate tree (1570, 3549), building on the site (403), abrasion of the tree trunks (3249), and cultivation (3250)

Status: Eight of the old localities were investigated. The species was present in seven and was regarded as uncertain in one. Seven new localities were discovered. The aggregate can be considered as rather common in old, oceanic Pinus sylvestris woodlands in Hordaland south of Bergen (e.g. in 1570, 3251, 3549). There is one small population in a nature reserve (409)

Notes: Usnea fragilescens s. str., U. cornuta and U. flammea are here treated collectively since the complex is in need of further study. In Norway U. flammea appears to be the most common species of the aggregate..

Specimens in other herbaria, litterature, etc.