Loiseleuria procumbens (Ericaceae) in the Spanish Pyrenees

The paper analyses the distribution and occurrence conditions of Loiseleuria procumbens in the Spanish Pyrenees. The species represents a typical arctic-alpine element in the flora of Europe. In the Pyrenees it reaches its southernmost European localities. The Pyrenean populations of the species are not numerous in the majority of the localities. L. procumbens occurs most frequently in the alpine and subalpine zones, at altitudes between 2100 and 2650 m, with a minimum at 1750 m and a maximum at 2900 m. It has been reported nearly exclusively in the siliceous substrata, and predominantly on the north-facing slopes, on the regosols and/or on flat tops of rocks. It forms its own communities, mostly included into the Loiseleurio-Vaccinion alliance, and rarely enters associations of the Festucion airoidis and Rhododendro-Vaccinion alliances. Its typical community, Cetrario-Loiseleurietum procumbentis, is found only in the eastern and central parts of the Spanish Pyrenees