(ancient Greek name). Cistaceae. Rock Rose. Low shrubs grown for their red or white hairy flowers.

Plants usually with villous and glandular tomentum, aromatic: leaves opposite, mostly persistent, entire, the opposite petioles connate at the base: flowers large, in terminal and axillary cymes at the end of the branches, rarely solitary, white to purple; sepals 3 or 5; petals 5; stamens numerous; style elongated or short with a large 5-10-lobed stigma: caps, many-seeded, splitting into 5 valves. - About 20 species in the Medit. region and many natural and garden hybrids. Monograph by Grosser in Engler, Pflanzenreich, hft. 14, pp. 10-32 (1903) and an illustrated monograph by R. Sweet, Cistineae (1825-30) quoted below as S.C.

The cistuses are ornamental free-flowering shrubs, usually only a few feet high, with very showy purple or white flowers similar to a small single rose, appearing in early summer. They are hardy only in warmer temperate regions, but many of them will stand 10° of frost without injury, and C. laurifolius and C. villosus variety tauricus even more. They thrive best in a well-drained light soil, mostly preferring limestone soil, and in a sunny position; the dwarfer species are well adapted for rockeries with southern aspect. They do not bear transplanting well, and should be grown in pots until planted out. Some species yield ladanum, a resin used in perfumery. Propagated by seeds sown in spring in pans or boxes and the young seedlings shaded; increased also by layers and cuttings in spring or late summer, inserted in sandy peat under glass. In the Old World, the cistuses are important garden plants, but they are little known in America.

a. Color of flowers purple or red.

B. Flowers l 1/2-2 in. wide; petals imbricate.

c. Leaves penninerved, 3-nerved only at the base.

d. Petals without a dark blotch at the base.

1. Villosus, Linn

(C. incanus, Linn.). Erect shrub, 3-4 ft., villous or tomentose: leaves penninerved, roundish-ovate or oblong, narrowed into a very short petiole, rugose above and grayish green, tomentose or villous beneath, 1-2 in. long: flowers 1-3, long-peduncled, reddish purple, 2 in. wide; petals light pink or yellowish at the base. May, June. Medit. region. B.M.43. S.C. 35. Gn. 27, p. 571. - A very variable species. variety creticus, Boiss. Leaves smaller, more spatulate at the base, very rugose, undulate at the margin: flowers purple. S. E. Eu., Asia Minor. Sibthorp, Flower Graeca 5:495. S.C. 112. Gn. 27, p. 571; 33, p. 490.

Variety rotundifolius, Loud. Dwarfer, with more roundish leaves S.C. 75. Garden form. variety tauricus, Grosser (C. tauricus, Presl). Leaves obovate-spatulate, the upper ones lanceolate, scarcely undulate: pedicels twice as long as sepals. Asia Minor. variety undulatus, Dunal. Leaves linear-oblong, acute, undulate: flowers solitary. S.C. 63. Garden form.

2. Heterophyllus, Desf

Erect, to 2 ft.: leaves short-petioled, elliptic- or oval-lanceolate, green on both sides and slightly hairy, 1/2-1 in. long: flowers 1-3, 2 in. wide; petals red, yellow at the base. N. Africa S.C. 6. - More tender.

dd. Petals with a dark blotch at the base.

3. Purpureus, Lam

(C. ladaniferus x C. villosus). Shrub to 4 ft., somewhat glutinous: leaves nearly sessile, lanceolate or oblong-lanceolate, acute, rugose above, slightly undulate and revolute at the margin, 1-2 in. long: flowers usually 3, lilac-purple, 3 in. across, the petals yellow at the base and with a maroon blotch. Of garden origin. Gn. 31:326; 45, p. 33; 53, p. 134. B.R. 5:408. S.C. 17. G.C. III. 48:118-19-One of the most beautiful rock roses.

cc. Leaves 3-nerved to the apex.

4. Crispus, Linn

Compact shrub, to 2 ft., villous: leaves sessile, linear-lanceolate or oblong-elliptic, undulate, rugose above, villous beneath: flowers 3-4, nearly sessile, 1 1/2-2 in. wide, deep rose-colored. June-Aug. S.W. Eu. S.C. 22. Gn. 34:252.

5. Albidus, Linn

Shrub to 4 ft., the young parts white-tomentose: leaves sessile, elliptic or ovate-oblong, revolute at the margin, reticulate beneath, whitish tomentose, 1/2-2 in. long: flowers 3-6, lilac or rosy, 21/2 in. across; style longer than stamens. S.W. Eu. N. Africa S.C. 31. G.C. III. 45:117. G.M. 51:783.

bb. Flowers 1 in. wide; petals not imbricate.

6. Parviflorus, Lam

Much-branched shrub, 1-2 ft.; tomentose: leaves 3-nerved, elliptic-ovate, undulate, rugose above, reticulate beneath, twisted, 1 in. long: flowers 3-5; petals pale rose, yellow at the base. June. Greece, Crete. S.C. 14.

aa. Color of flowers white: leaves 3-nerved.

b. Sepals 3.

c. Leaves nearly sessile: plant very glutinous: flowers usually solitary.

7. Ladaniferus, Linn

Shrub, to 4 ft., glutinous: leaves lanceolate, glabrous and viscid above, whitish tomentose beneath, 1 1/2-4 in. long: flowers usually solitary, long-peduncled, 3-3 1/2 in. wide; petals yellow at the base. June. S. W. Eu. S.C. 84. F.S.R. 2, p. 44. G. 22:213. Gn. 58, p. 171; 66, p. 257. F. 1874, p. 160. variety maculatus, Sweet. Petals with a dark brownish crimson spot above the base. Gn. 30:30; 33, p. 490. S.C. 1. G. 26:598. Grosser 23. - Probably the most beautiful of all cistuses.

cc. Leaves distinctly petioled: flowers several.

8. Cyprius, Lam

(C. ladaniferus x C. laurifolius). Erect shrub, to 6 ft., somewhat glutinous: leaves oblong-lanceolate, glabrous above, villous- tomentose beneath: flowers 5-7, nearly 3 in. wide; petals blotched purple at the base. June. Garden origin. S.C. 39. Gn. 76, p. 438. B.M. 112 (as C. ladaniferus).

9. Laurifolius, Linn

Fig. 969. Shrub to 6 ft.: leaves petioled, ovate or ovate - lanceolate, glabrous above, whitish or brownish tomentose beneath, 1-2 1/2 in. long: flowers 3-8, 2-3 in. wide; petals with yellow blotch. June-Aug. S. W. Eu. Gn. 53, p. 131; 64, p. 234. G.M. 34: 95. S.C.52- The hardiest species.

bb. Sepals 5.

10. Salvifolius, Linn

Shrub,to 2 ft., sometimes procumbent: leaves petioled, oval to ovate-oblong, rigid, very rugose above, tomentose on both sides, 1/2-1 3/4in long; bracts deciduous: flowers solitary or several, white, I 1/2 in. across. S. Eu., N. Africa, Orient. S.C. 54. Gn. 76, p. 352. G. 30:593. - A very variable species.

Cistus laurifolius. (X 1/5)

Fig. 969. Cistus laurifolius. (X 1/5)

11. Populifolius, Linn

(C. cordifolius, Mill. C. Cupanianus, Presl). Shrub to 6 ft.: leaves long-petioled, cordate-ovate, acuminate, penninerved, rugose, glabrous, 2-3 1/2 in. long: flowers 2-5, white, 2 in. across. S. W. Eu. S.C. 23, 70.

C. algarvinsis, Sims=Helianthemum ocymoides. - C. candidis-simus, Dun.; S.C. 3=C. symphytifolius, variety - C. canescens, Sweet (C. villosus variety canescens, Nichols. C. albidusxC. villosus). Leaves short-petioled, narrow-oblong or lanceolate, 3-nerved, obtuse, undulate: flowers dark purple. Of garden origin. S.C. 45. - C. Clusii, Dun.=C. rosmarinifolius. - C. corbariinsis, Pourr. (C. populifolius XC. salvifolius). To 5 ft.: leaves slightly cordate, glutinous: flowers 1-5, white, 1 1/2 in. S.C. 8. - C. florentinus, Lam. (C. monspeliensis X C. salvifolius). Dwarf: leaves lanceolate: flowers white, 2 in. S.C. 59. G. 11:183; 14:241. G.M. 32:277; 31:587. Gn. 27:570; 38, p. 177; 53, p. 130, 134; 75, p. 422. F.S.R. 2, p. 43. - C. formosus, Curt.= Helianthemum formosum. - C. glaucus, Pourr. (C. Ledon, Lam. C. laurifoliusXC. monspeliensis). 1-2 ft!: leaves lanceolate, glossy above: flowers 5-10, white, 1 1/2 in- S. France. - C. hirsutus, Lam. 1-3 ft., clothed with spreading and glandular hairs: leaves sessile, lanceolate: flowers 1-5, white.

S.W. Eu. S.C. 19. - C. latifblius, Sweet, S.C. 15=C. populifolius variety - C. Iaxus, Ait.=C. nigricans. - C. Ledon, Lam.=C. glaucus. - C. longifolius, Lam.=C. nigricans. - C. Loretii, Rouy & Fouc. (C. ladaniferus X C. monspeliensis). Habit like C. monspeliensis: leaves linear-lanceolate, revolute, grayish beneath, glutinous: flowers 1-5, white, 2 in. across. Of garden origin; also found spontaneous. variety maculatus, Rouy & Fouc. Flowers with 5 dark red blotches. Gn. 75, p. 633; 76, p. 439. - C. monspeliensis, Linn. To 5 ft.: leaves sessile, lanceolate: flowers white, cymose, 1 in. S. Eu. S.C. 27. - C. nigricans, Pourr. (C. longifolius, Lam. C. laxus, Ait. C. monspeliensisXC. populifolius). 2-4 ft., glandular: leaves oblong-lanceolate, glossy above: flowers white, 1 1/2in- S.W. Eu. S.C. 12. Variable. - C. oblongifolius, Sweet; S.C. 67=C. nigricans variety - C. obtusifolius, Sweet, S.C. 42-C. nigricans variety -C. rosmarinifolius, Pourr. (C. Clusii, Dun.) Allied to C. ladaniferus. Leaves linear, strongly revolute at the margin, viscid above while young, tomentose beneath: flowers 4-6, white, 1-1 1/3 in. across. W. Medit. region.

S.C. 32. G.M. 31:587; 32:277. - C. symphyti-fdlius, Lam. (C. vaginatus, Dry. Rhodocistus Berthelotianus, Spach). To 2 ft.: leaves petioled, ovate, acuminate: flowers cymose, deep rose-colored, yellow in center. Canary Isls. S.C. 9. B.R. 3:225. F.S. 15:1501. - C. vaginatus, Dry.=C. symphytifolius.

Alfred Rehder.