Description from Flora of China
Ketmia arborea Moench, nom. illeg. superfl.; K. syriaca (Linnaeus) Scopoli; K. syrorum Moench, nom. illeg. superfl..
Shrubs deciduous, erect, 1.5-4 m tall. Branchlets yellow stellate puberulent. Stipules filiform-subulate, ca. 6 mm, pilose; petiole 5-25 mm, stellate pubescent adaxially; leaf blade rhomboid to triangular-ovate or broadly lanceolate, variously 3-lobed or entire, 3-10 × 2-4 cm, papery, abaxially puberulent along veins or glabrous, adaxially glabrous, basal veins 3-5, base cuneate, margin irregularly incised, apex obtuse to subacute. Flowers solitary, axillary on upper branches. Pedicel 4-14 mm, stellate puberulent. Epicalyx lobes 6-8, filiform, 6-20 × 0.5-2 mm, ± free, connate at base only, densely stellate puberulent, apex obtuse or acute. Calyx campanulate, 14-20 mm, densely stellate puberulent, lobes 5, triangular. Corolla blue-purple, violet, white, pink, or reddish, sometimes with darker center, campanulate, sometimes double, 5-6 cm in diam.; petals obovate, 3.5-4.5 cm, pilose and stellate villous abaxially. Staminal column ca. 3 cm. Style glabrous. Capsule ovoid-globose, ca. 12 mm in diam., densely yellow stellate puberulent. Seeds reniform, with yellow-white hairs abaxially. Fl. Jul-Oct.
Despite the specific epithet, Hibiscus syriacus originated in China but was taken into cultivation very early and was distributed to the Middle East along early trade routes. It is a very popular frost-hardy flowering shrub from which many named cultivars have been developed, some of which have been given formal scientific names. These include:
H. syriacus var. alboplenus Loudon (白花重瓣木槿 bai hua chong ban mu jin): Flowers double, white, 6-10 cm in diam.
H. syriacus var. amplissimus L. F. Gagnepain (粉紫重瓣木槿 fen zi chong ban mu jin): Flowers double, pink-purple with red center.
H. syriacus var. brevibracteatus S. Y. Hu (短苞木槿 duan bao mu jin): Leaf blade rhomboid, base cuneate. Flowers single, purplish. Epicalyx lobes very small, 3-5 × 0.5-1 mm, silky.
H. syriacus var. elegantissimus L. F. Gagnepain (雅致木槿 ya zhi mu jin): Flowers double, pink, 6-7 cm in diam.
H. syriacus var. grandiflorus Rehder (大花木槿 da hua mu jin): Flowers single, peach or red.
H. syriacus var. longibracteatus S. Y. Hu (长苞木槿 chang bao mu jin): Flowers single, purplish. Epicalyx lobes nearly as long as sepals, 15-20 × 1-2 mm.
H. syriacus var. paeoniiflorus L. F. Gagnepain (牡丹木槿 mu dan mu jin): Flowers double, pink or purplish, 7-9 cm in diam.
H. syriacus var. totoalbus T. Moore (白花牡丹木槿 bai hua dan ban mu jin): Flowers single, white.
H. syriacus var. violaceus L. F. Gagnepain (紫花重瓣木槿 zi hua chong ban mu jin): Flowers double, greenish purple.
● Sea cliffs, hillsides, along streams, roadsides, also extensively cultivated; below 1200 m. Native in Anhui, Guangdong, Guangxi, Jiangsu, Sichuan, Taiwan, Yunnan, and Zhejiang; cultivated in Fujian, Guizhou, Hainan, Hebei, Henan, Hubei, Hunan, Jiangxi, Shaanxi, Shandong, and Xizang [cultivated in most tropical and temperate regions].