An annual of upland rocky flushes, seepage areas and wet rock ledges on montane cliffs. It grows from 380 m at Langstrath (Westmorland) to c. 750 m on Snowdon (Caerns.).
E. rivularis is diploid and is closely allied to E. rostkoviana, from which it has probably arisen through hybridisation with E. micrantha. Its distribution appears to be stable in the Lake District, but the species seems to have declined in Wales where recent searches have failed to re-find it in many known sites.
Count of 10km squares in Great Britain: 14
Count of 10km squares in Ireland: 0
Count of 10km squares in the Channel Isles: 0
RDB Species Accounts
Euphrasia rivularis Pugsley (Scrophulariaceae)
Eyebright, Effros Yr Wyddfa
Status in Britain: LOWER RISK - Near Threatened. ENDEMIC.
E. rivularis is confined to higher altitudes in Snowdonia and the Lake District. It occurs in bryophyte-rich flushes by streams, on wet, flushed slopes and on wet ledge and seepage areas on montane cliffs. In Snowdonia, it can be an attractive feature of the same basic rock-faces that support Lloydia serotina and other arctic-alpines. Associated species include Arabis petraea, Campanula rotundifolia, Festuca vivipara, Selaginella selaginoides, Thalictrum alpinum and T. minus. It may also be accompanied by E. ostenfeldii, which replaces it on the drier ledges. On flushed turfy slopes, associates include Agrostis capillaris, Carex viridula ssp. oedocarpa, Danthonia decumbens, Epilobium brunnescens, Festuca ovina ssp. hirtula, Nardus stricta, Potentilla erecta, Sagina procumbens, Saxifraga hypnoides, Hylocomium splendens, Polytrichum formosum, Scleropodium purum and Thuidium tamariscinum, with Euphrasia cambrica sometimes present on the flush margins and surrounding drier turf. In the Lake District it may be more a species of the streamside flushes, again with C. viridula ssp. oedocarpa and other sedges.
E. rivularis is closely allied to E. officinalis sensu stricto, (including E. rostkoviana and E. montana) and may have arisen by hybridisation between one of these taxa and a tetraploid species. However, it exists as a clearly defined, independent taxon with distinctive, uniform populations. There is some variation between individual, isolated populations, as frequently occurs in alpine species.
It is a medium- to relatively large-flowered outcrossing species, but usually well isolated from other diploid species with which it might exchange genes. Hybrids are consequently rare. A single plant of E. rivularis x (confusa x scottica) has been noted at Cwm Idwal, where E. rivularis occurs as part of a complex population, and it is also known to be crossing with E. rostkoviana (probably ssp. rostkoviana) at one site in the Lake District. These hybridisation events pose no threat to the species, which is one of the most well delimited of the British taxa.
In Snowdonia, key populations lie within NNRs and appear to be subject to no obvious threat, particularly as the species is able to survive under both light and heavier grazing conditions. In the Lake District, the plant is now known in numerous localities and again seems subject to no immediate threat.
A. J. Silverside
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.