Description from Flora of China
Shrubs deciduous, erect, 2-4 m tall. Branchlets stellate puberulent when young. Stipules filiform, ca. 12 mm, stellate pilose; petiole 3-6 cm, stellate puberulent; leaf blade cuneate, ovate, or orbicular, usually 3-lobed, 7-12 × 7-12 cm, papery, basal veins 3-5, both surfaces sparsely stellate puberulent, lobes usually triangular, central lobe larger, base cuneate, broadly cuneate, or nearly rounded, margin acutely serrate. Flowers solitary, axillary on upper branches. Pedicel 1-2.5 cm, densely yellow stellate puberulent. Epicalyx lobes 6 or 7, lanceolate-oblong, free, connate at base only, 17-25 × 3-5 mm, densely stellate puberulent, apex obtuse or acute. Calyx campanulate, longer or shorter than epicalyx, lobes 5, ovate-triangular, densely golden stellate puberulent. Corolla purplish, 7-9 cm in diam.; petals obovate, 6-7 cm, stellate villous abaxially. Staminal column 4-5 cm. Style branches 5, glabrous. Fruit unknown. Fl. Jun-Jul.
Hibiscus sinosyriacus is very similar to H. syriacus. The main differences are the broader epicalyx lobes (3-5 mm, not 0.5-2 mm, wide), larger petals (6-7 cm, not 3.5-4.5 cm), and wider leaves (7-12 cm, not 2-4 cm, wide). It is also similar to H. labordei but differs from that species in having the leaf base cuneate to nearly rounded, not rounded to slightly cordate, and the style branches glabrous, not hirsute.
● Scrub in valleys; 500-1000 m. Guangxi, Guizhou, Hunan (Hengshan, Qianyang), Jiangxi (Lushan).