6. Sida alnifolia Linnaeus, Sp. Pl. 2: 684. 1753.
桤叶黄花稔 qi ye huang hua ren
Subshrub or shrubs erect, 1-2 m tall. Branchlets thin, stellate pilose. Stipules subulate, usually shorter than petiole; petiole 2-8 mm, stellate pilose; leaf blade obovate, ovate, ovate-lanceolate, or nearly orbicular, 2-5 × 0.3-3 cm, abaxially stellate velutinous, adaxially stellate pilose, base rounded to cuneate, margin regularly dentate to crenately serrulate, apex acute to rounded. Flowers solitary, axillary. Pedicel to 3 cm, articulate in distal 1/2, densely stellate tomentose. Calyx cup-shaped, 6-8 mm, stellate tomentose, lobes triangular. Corolla yellow, ca. 1 cm in diam.; petals obovate, ca. 1 cm. Filament tube 4-5 mm, hirsute. Schizocarp subglobose; mericarps 6-8, ca. 3 mm, hairy, apex 2-awned. Fl. Jul-Dec.
Fujian, Guangdong, Guangxi, Hainan, Jiangxi, Taiwan, Yunnan [India, Thailand, Vietnam].
This species is very similar to Sida rhombifolia. It differs in having a hirsute filament tube and 6-8 mericarps per flower, while S. rhombifolia has a glabrous filament tube and 8-10 mericarps. It has been confused with S. fallax Walpers, described from Hawaii. The treatment of the taxa included within this species has varied greatly between all the accounts that have dealt with them. Four varieties are tentatively accepted here but as with S. rhombifolia there is a need for much more detailed studies.