Arabidopsis petraea Northern Rock-cress RR DDD N
I find A. petraea on ledges or growing out of cracks on mountain rocks and because it is one of many similar white crucifers, you need to get close for a positive identification which isn't always easy. The flowers are not entirely dissimilar to A caucasica (Garden Arabis) which grows abundantly on the limestone rocks of the White Peak in Derbyshire, but the leaves are quite different. This plant was very conveniently only 4 feet off the ground growing out of a crack on cliffs below Snowdon summit.
Arabidopsis petraea is absent from England and only occurs in Snowdonia in Wales. Apart from a couple of sites in Ireland the rest of the population are to be found in Scotland most frequently on the Cairngorms and on the mountains of Skye.
The name has recently changed (New Flora of the British Isles Third Edition by Clive Stace 2010) from Arabis petraea to Arabidopsis petraea.
Cliffs near Snowdon, North Wales, 2nd June 2004
Added on 1st Nov 04, amended on 16th Nov 04, updated 4th Oct 08, updated 27th Feb 2010, updated Se3 25th Apr 10