North Pennines AONB Partnership
Calaminarian grassland is named after Viola calaminaria, a plant found growing in grasslands on metal-rich soils in continental Europe, itself named after the zinc ore calamine. Although the violet itself is not found in the UK, the country contains almost 30 per cent of Europe’s calaminarian grassland.[1]
There are estimated to be about 109 ha (269 acres) of calaminarian grassland in the UK, almost half of it in the North Pennines. Most calaminarian grasslands are anthropogenic in origin, associated with heavy metal mining and in particular the disposal of contaminated mine waste.[2] In a few places, mainly in the Scottish Highlands, they occur naturally where thin soil sits over rock containing exposed mineral veins.[1]
Species tolerant of high levels of heavy metals are known as metallophytes.[1] They include spring sandwort (Minuartia verna), field pennycress (Thlaspi arvense), and genetically adapted species such as thrift (Armeria maritima) and bladder campion (Silene uniflora). Other notable species include Young’s helleborine (Epipactis youngiana), forked spleenwort (Asplenium septentrionale), Cornish path-moss (Ditrichum cornubicum), western rustwort (Marsupella profunda), Cephaloziella nicholsonii, Ditrichum plumbicola, Scottish sandwort (Arenaria norvegica) and Shetland mouse-ear (Cerastium nigrescens).[3]