An evergreen shrub 3 to 5 ft high, of erect, thin habit; branches very clammy with a shining resin. Leaves three-nerved, glutinous, linear-lanceolate, 11⁄2 to 4 in. long, 1⁄4 to 3⁄4 in. wide; tapering gradually to both ends, scarcely stalked, the bases of each pair clasping the stem; dark green and glabrous above, covered beneath with a close grey felt. Flowers solitary at the end of slender side twigs, protected in the bud state by large bracts, white, with a fine blood-red blotch at the base of each petal, 3 to 4 in. across, the petals crimped at the margin. Sepals three, large, concave, covered with yellowish scales. Seed-vessel ten-valved.
Native of S. Europe and N. Africa; introduced in 1629. Near London this rock rose withstands frosts up to 20°, but is certainly not so hardy as C. × cyprius, nor so vigorous and bushy a plant. It is a beautiful species, especially the common crimson-blotched form, and has larger flowers than any other species we can cultivate out-of-doors. It differs from C. laurifolius in its narrow leaves, in the absence of hairs on the stem and flower-stalks, in the scaly sepals, and in the solitary flowers. (See also C. × cyprius.) There is a pure white, unspotted form of the species known as var. albiflorus (Dunal) Dansereau. It is said to be commoner in the wild than the blotched form.
var. petiolatus Maire – Leaves shortly stalked; valves of capsule usually less than ten. This variety, native of N. Africa, also lacks the characteristic gum of the type. Dansereau considers that it may be the result of past hybridisation between C. ladanifer and C. laurifolius.
C. ladanifer, mostly in its blotched form, is the parent of most of the cistus hybrids commonly seen in gardens: see C. × cyprius, C. × lusitanicus, and C. × purpureus. The following are also cultivated:
C. × aguilari Pau – A hybrid between C. ladanifer and C. populifolius, found wild in the Iberian peninsula and in Morocco; introduced, in an un-blotched form, by Sir O. Warburg. Leaves lanceolate, to 4 in. long, short-stalked, bright green above, paler below, three-nerved and strongly net-veined; margins closely undulate. It was collected in S. Spain and the second parent was C. populifolius var. lasiocalyx.
A blotched form of C. × aguilari – ‘Maculatus’ – was raised by Sir O. Warburg and received an Award of Merit in 1936. The parentage was given as C. ladanifer (blotched form) × C. populifolius var. lasiocalyx, but there is a possibility that C. × aguilari itself was the second parent (Gard. Chron., 26th March 1960, p. 187). It resembles the unspotted form in foliage, but the leaves are decidedly gummy, suggesting a stronger influence of C. ladanifer. Both forms of C. × aguilari are among the finest of cistuses, but not reliably hardy and apt to become top-heavy and blow over. Their flowers are of more substance than in most cistuses and the rippled leaves, of a cheerful green, render them very striking and decorative even when out of flower.
C. × hetieri Verguin – A triple hybrid between C. ladanifer, laurifolius, and monspeliensis. An erect, free-flowering, and pleasing hardy shrub of garden origin, which has also been found wild in France.
C. × loretii Rouy & Fouc. – A hybrid between C. ladanifer and C. monspeliensis which has been found wild and also raised in gardens. There is a spotted form in commerce with flowers about the size of those of C. monspeliensis and with linear-lanceolate leaves, intermediate between those of the parents. The plant once grown in gardens as “C. loretii” is C. × lusitanicus ‘Decumbens’.
C. (ladanifer × palhinhae). – Shortly after introducing C. palhinhae, Capt. Ingram crossed it with a particularly fine (but tender) blotched form of C. ladanifer found by him in S.W. Spain in 1936. From the original cross and later seedlings from it he raised ‘Paladin’ (Award of Merit 1946), ‘Pat’ (Award of Merit 1955), both with blotched flowers, and ‘Blanche’ (Award of Merit 1967), in which the flowers are unblotched. These hybrids, although rather tender, have the great merit of combining the beautiful flowers of C. ladanifer with a bushy and spreading habit of growth. This should render them more suitable for coastal gardens of the south and west than C. ladanifer and some of its other hybrids, which are inclined to become leggy, and to blow over in exposed positions.
C. × verguinii Coste & Soulié – A very rare natural hybrid between C. ladanifer and C. salviifolius. Flowers white, with a fine warm blotch. There is also an unblotched form in cultivation.