Description from Flora of China
Geranium platypetalum Franchet, Pl. Delavay. 111. 1889, not Fischer & C. A. Meyer (1835); G. mairei H. Léveillé; G. pinetorum Handel-Mazzetti; G. terminale Z. M. Tan.
Perennials. Rootstock ± horizontal, 0.9-1.3 cm in diam., not tuberculate, with thickened roots along rootstock. Stem 34-89 cm tall, erect, not rooting at nodes, with 0.3-0.8(-1.7) mm retrorse ± appressed nonglandular trichomes and sometimes 0.4-1.5 mm patent glandular trichomes. Stipules broadly lanceolate, connate at least at base. Leaves opposite; petiole with 0.3-0.6(-2.3) mm retrorse appressed nonglandular trichomes; leaf blade 4.2-12 cm, palmately cleft, ratio of main sinus/middle segment length = 0.76-0.9, pilose with appressed nonglandular trichomes; segments 5, rhombic, 5.1-11.1 mm wide at base, 9-25-lobed in distal half, ratio of second sinus/middle segment length = 0.06-0.2. Cymules solitary or in aggregates at apex of each branch, 2-flowered; peduncle (0-)1.7-8.2 cm. Pedicel 1.4-2.9 cm, with 0.3-0.5 mm uncinate nonglandular trichomes and 0.3-1.6 mm patent glandular trichomes; bracteoles filiform. Sepals 5.6-9.2 mm, mucro 0.8-2 mm, ratio of mucro/sepal length = 0.13-0.26, outside with 0.3-0.7 mm antrorse ± appressed nonglandular trichomes and 0.4-1.6 mm patent glandular trichomes, inside glabrous. Petals blackish red with a pale pink base, (6.7-)7-8.1(-9.3) mm, reflexed, both surfaces glabrous or rarely outside with a few trichomes, margin with sparse cilia, apex rounded. Staminal filaments dark red, lanceolate, abaxially sparsely pilose and proximal half ciliate, trichomes 0.2-0.4(-0.8) mm; anthers blackish, 2.1-2.5 mm. Nectaries forming a ring around flower, glabrous. Stigma dark red. Fruit 2.4-3 cm, nodding when immature; mericarps smooth, with a basal callus, with 0.4-1.7 mm ± patent nonglandular trichomes; rostrum 1.6-2.2 cm, with a 5.2-6.6 mm narrowed apex; stigmatic remains 1.9-2.5 mm. Seeds 2.7-3 mm. Fl. Jun-Jul, fr. Sep-Oct. 2n = 28*.
This is the only species in the genus with a nectary forming a ring all around the flower. Flower features such as blackish, reflexed petals as long as wide, with sparse trichomes on the margin, and almost glabrous staminal filaments further help to identify Geranium sinense. Glandular trichomes are finer than in G. refractum and are not purple except for the head. The type of G. pinetorum shows all of these characters. Pollen has no deformation and fruit are well developed, which does not support Yeo’s view (Edinburgh J. Bot. 49: 169. 1992) that G. pinetorum could be a hybrid. For these reasons, it is here considered as synonym of G. sinense.
The rhizomes are used as a Chinese medicine for dysentery.
● Secondary forests, meadows; 2300-3500(-4600) m. SW Sichuan, NW Yunnan.