A small, densely tufted perennial herb found in bare or bryophyte- or lichen-rich places on mountains on shallow soil or in rock crevices, on both acidic and calcareous substrata. J. trifidus is one of the principal angiosperms of wind-swept, often almost snow-free plateau edges over c. 1000 m, but it also occupies sites that are snow-covered for several months. From 240 m on Ronas Hill (Shetland) to 1310 m in the Cairngorms.
The distribution of J. trifidus is stable.
Eurosiberian Arctic-montane element; also in N. America.
Light (Ellenberg): 8
Moisture (Ellenberg): 5
Reaction (Ellenberg): 2
Nitrogen (Ellenberg): 2
Salt Tolerance (Ellenberg): 0
January Mean Temperature (Celsius): 1
July Mean Temperature (Celsius): 11.5
Annual Precipitation (mm): 2162
Count of 10km squares in Great Britain: 177
Count of 10km squares in Ireland: 0
Count of 10km squares in the Channel Isles: 0
Atlas Change Index: -0.38
PLANTATT - Attributes of British and Irish plants. (.zip 1455KB) This dataset was compiled and published in 2004, and last updated in November 2008. Download includes an Excel spreadsheet of the attributes, and a PDF explaining the background and nomenclature. Note that the PDF version is the booklet as published, whereas the Excel spreadsheet incorporates subsequent corrections. A hardcopy can be purchased from the Centre for Ecology and Hydrology.
Atlas text references
1986. Atlas of north European vascular plants north of the Tropic of Cancer. 3 vols.
1958. The ecology of the Cairngorms, IV. The Juncus zone: Juncus trifidus communities. Journal of Ecology. 46:707-737.
1962. Plant communities of the Scottish Highlands. Monographs of the Nature Conservancy No. 1.
1965. Vergleichende Chorologie der zentraleuropäischen Flora. Volume 1. 2 vols.