Iberis gibraltarica L.

An evergreen, flat-topped, half-woody plant up to 12 in. high or sometimes more, and in favourable localities as much as 2 or 3 ft in diameter. Leaves linear-obovate, 3⁄4 to 2 in. long, 1⁄4 to 1⁄2 in. wide, rounded at the apex and usually although often inconspicuously toothed on the terminal half, gradually tapered towards the base, glabrous. On the flower-stems the leaves decrease in size, finally becoming linear and about 1⁄8 in. wide. Flower-stems 6 to 8 in. long, often branched towards the top. Flowers crowded in flattish umbel-like clusters 2 to 3 in. wide; white or reddish lilac, or both, with the paler ones in the centre. The two outer petals are much larger than the two inner ones and those of the outermost flowers may be 1⁄2 to 3⁄4 in. long. The flat seed-pod is about 3⁄8 in. long, notched at the top. Bot. Mag., t. 124.

Native of S. Spain and Morocco, its best-known habitat being the Rock of Gibraltar, from which it takes its specific name; introduced in 1732. It grows in crevices and holes in the face of the cliffs, where to all appearance there is no soil. The true plant is not common, although other species often may be seen under this name. It is very suitable for sunny gardens on the south coast, planted in full sun in a light soil with which stones or rubble have been freely mixed. In colder parts it survives only mild or moderately severe winters. It blossoms from May to July. From the other species it can be distinguished by its usually branched flower-stems, usually toothed leaves, and more highly coloured flowers.