ROCK ROSE

(Cistus), any of a genus of 17 species of low to medium-sized shrubs, in the rock rose family (Cistaceae), native to the Mediterranean region and long known to horticulture. There are a number of garden hybrids useful in warm areas, where they are often grown in rock gardens. The flowers are single and roselike, in white, pink, or rosy-purple, often with a yellowish or dark blotch at the base of the petals. Cistus ladanifer, called laudanum, has white petals, red-brown at the bases, and yields a resin used in perfumery. C. albidus, up to 2 metres (6 feet) high, has lilac- to rose-coloured flowers. C. palhinhae, a low shrub, reaching about 45 centimetres (1 1/2 feet), bears large white flowers up to 10 cm across. C. incanus, growing to about 1 m, has rose-pink flowers up to 6 cm across. The so-called sun roses, related plants of the genus Helianthemum (family Cistaceae), are also sometimes referred to as rock roses (see sun rose).