Related to : Thale Cress (Arabidopsis thaliana) and to Sand Rock-cress (Arabidopsis arenosa)

The plants growing on Serpentinic Rock on the Keen of Hamar, on Unst, Shetlands usually have differing characteristics to the same species which occur much further south on mainland Britain. They may be stunted and/or their leaves take on a differing form and shape (as in the specimens on this page) and various other differences. This is not fully understood but is most certainly due to a combination of features such as the much more inclement weather so far up North, the really rather rare serpentinic soil upon which they grow, plus the elementary composition of that soil - deficient in some minerals with an excess of other elements including some heavy metals.

See Keen of Hamar or Serpentinic Rocks for some reasons why plants groing on the Keen of Hamer often differ in form to the same species growing on mainland Britain. The fact that Thrift (a renown metallophyte which is able to sequester many differing heavy metals and stash them out of harms way) also grows on the Keen of Hamer is surely testament to the protection afforded by heavy metal concentrations if the plant has some mechanism for dealing with the heavy elements.

Northern Rock-cress is native and grows on rocky-ledges of mountains, mountain crevices and rocky slopes in North west Wales, North Central Scotland and extremely locally in Ireland.