Alyssum spinosum, now Hormathophylla spinosa (spiny madwort) is a species of flowering subshrub in the genus Alyssum of the family Brassicaceae, native to open rocky sites in south-eastern France and southern Spain. It forms a compact mound up to 30 cm in height. Dense spiny branches of tiny, toothed grey-green leaves bear racemes of white flowers at the tips in early summer. It is especially cultivated in rock gardens. The cultivar A. spinosum 'Roseum', with pink flowers, has gained the Royal Horticultural Society's Award of Garden Merit.