Arabis hirsuta, known as hairy rock-cress, is a flowering plant of the genus Arabis in the family Brassicaceae. In previous North American works, it has been broadly defined to include plants native to Europe, Asia, and the northern half of North America, but is now more often restricted to a narrower subgroup restricted to Europe.
This erect, 15–60 cm high hairy plant is usually unbranched, with a long spike of flowers. Lowert leaves form a rosette, the stalkless upper-leaves clasp the stem. The white petals are twice as long as the sepals, flowers June–August. The fruits are cylindrical and pressed close to the stem and the slightly winged seeds are reddish brown. The shape of its hairs are stiff and forking, like the frame of a child's catapult. It grows on chalk slopes, dunes, hedgebanks, walls and rocks.
^Robert Karl, Marcus A. Koch. Phylogenetic signatures of adaptation: The Arabis hirsuta species aggregate (Brassicaceae) revisited. Perspectives in Plant Ecology, Evolution and Systematics. in press. Available online 24 June 2014
^Reader's Digest Nature Lover's Library, Field Guide to the Wildflowers of Britain, Editor Michael W. Davison, Art Editor Neal V. Martin, The Reader's Digest Association Limited, 11 Westferry Circus, Canary Wharf, London E144HE, Reprint 2001, ISBN 0 276 42506 5.