River Wye / Afon Gwy IPA
Location: From the mid-Wales hills, east to Hereford and then south to join the Severn at Chepstow.
Grid Reference: SN 933 474/SO 511 126
From its source to its confluence the main channel is 250kms long and has the fourth largest flow of any river in England and Wales. Rising at an altitude of 680m on Pumlumon Fawr in Powys, the Wye meanders down through Wales, Herefordshire and Gloucestershire, finally entering the Severn Estuary at Chepstow. The river is important for bryophytes and lichens, in particular the rare river jelly lichen Collema dichotomum.
There is a clear transition between the upland reaches, with characteristic algae, mosses and liverworts to the vast water crowfoot beds of the meandering middle and lower sections. Here varied water-crowfoot and stream water-crowfoot are abundant, with other Ranunculus species, including the uncommon river water-crowfoot, found locally.
Other common plants include rigid hornwort and perfoliate pondweed. Rare aquatic species include whorled water milfoil. In the lower reaches of river through the Wye Gorge, the calcium and nutrient content of the water increases. Here, aquatic vegetation is mainly comprised of pondweed species such as fennel pondweed and curled pondweed. Marginal vegetation often consists of reed canary-grass and branched bur-reed. Other marginal plants such as amphibious water bistort, brooklime, yellow-cress and water forget-me-not are widespread and frequent.
The nationally scarce horse-tail may be found growing along the margins of the river in its upper section. Below Brockweir the upper mud banks of the river are colonised by salt-marsh species such as sea aster, saltmarsh-grass and sea-milkwort. Characteristic bankside plants include stinging nettle, great willowherb and reed canary-grass. Locally the river bank vegetation can be diverse containing species such as common black knapweed and comfrey. A number of rare and restricted species occur along the banks, including common meadow-rue, meadow saxifrage and chives. The latter species grows in deep crevices in riverside outcrops and bedrock.