Description from Flora of China
Shrubs deciduous. Winter buds small, with 2–8 exposed scales. Leaves alternate, usually shortly petiolate, simple; stipules absent; leaf blade veins usually pinnate, rarely 3–5 from base, margin serrate or incised, sometimes lobed, rarely entire. Flowers in umbels, umbel-like racemes, corymbs, or panicles, bisexual, rarely ± unisexual. Hypanthium campanulate or cupular, lined by nectariferous disk. Sepals 5, valvate or slightly imbricate, usually slightly shorter than hypanthium. Petals 5, imbricate or contorted, usually longer than sepals. Stamens 15–60, borne between disk and petals. Disk annular, usually lobed. Carpels (3–)5(–8), free; ovules (2 to) several per carpel, pendulous; styles terminal, subterminal, or abaxial; stigma capitate or disciform. Follicles bony, often dehiscent along adaxial suture. Seeds linear to oblong, minute; testa membranous.
Spiraea holorhodantha H. Léveillé (Bull. Acad. Int. Géogr. Bot. 25: 44. 1915), described from Yunnan, is Rodgersia sambucifolia Hemsley var. sambucifolia in the Saxifragaceae (see Fl. China 8: 274. 2001).
Many of the following species are ornamental, nectar-secreting plants long established in horticulture and often cultivated in gardens and parks.
In the following key, leads 1a and 1b are not quite mutually exclusive. If identifying plants with short, lateral inflorescences, it is advisable to work from lead 3a as well as 1b.
Between 80 and 100 species: N temperate zone, extending S to mountainous subtropical areas; 70 species (47 endemic) in China.
(Authors: Lu Lingdi (Lu Ling-ti); Crinan Alexander)