Description from Flora of China
Geranium eriophorum H. Léveillé.
Biennials or sometimes annuals. Stem 10-55 cm tall, erect, not rooting at nodes, with 0.4-1 mm ± patent glandular trichomes. Stipules ovate, distinct. Leaves opposite; petiole with 0.3-0.5 mm retrorse not appressed nonglandular trichomes and 0.4-2.4 mm patent glandular trichomes; leaf blade 3-9 cm, palmately divided, pilose with ± appressed glandular trichomes; segments 5, rhombic, with a petiolule on middle segment 0.2-0.4 × as long as its segment, 16-46-lobed in distal half, ratio of second sinus/middle segment length = 0.26-0.5. Cymules solitary, 2-flowered; peduncle 1-6 cm. Pedicel 0.5-2 cm, with 0.4-1.5 mm patent glandular trichomes and 0.3-0.5 mm retrorse not appressed nonglandular trichomes; bracteoles lanceolate. Sepals 6-8 mm, mucro 1.8-2.5 mm, ratio of mucro/sepal length = ca. 0.3, outside with 0.3-0.5 mm ± patent nonglandular trichomes and 0.4-3.2 mm patent glandular trichomes, inside glabrous. Petals purplish, 7.5-9.7(-10.4) mm, erect to patent, glabrous, apex rounded. Staminal filaments pinkish, lanceolate with an abruptly narrowed apex, glabrous; anthers purplish, 0.4-0.6 mm. Nectaries 5, hemispheric, glabrous. Stigma pinkish. Fruit 1.9-2.3 cm, erect when immature; mericarps reticulate, ridges sparse and scarcely anastomosing in basal half but denser apically and forming 1 or 2(or 3) overlapping collar-like keels at apex, without a basal callus, glabrous or sometimes with ca. 0.2 mm nonglandular trichomes, small glands, or both; rostrum 1.7-1.9 cm, with a 4-5 mm narrowed apex; stigmatic remains 1-1.3 mm. Seeds 2.1-2.2 mm. Fl. Apr-Jun, fr. May-Aug. 2n = 64.
Petals of Chinese specimens of Geranium robertianum are unusually short. In other areas, petals vary from 0.9 to 1.4 cm. Geranium purpureum Villars, which is not recorded from China, is quite similar to G. robertianum and has short petals. However, it can be separated by its yellow anthers and by its mericarps closely ribbed. Geranium purpureum is widespread in N Africa, Europe, and W Asia as far as Iran.
Forests; 900-3300 m. Guizhou, Hubei, Hunan, Sichuan, Taiwan, Xizang, Yunnan, Zhejiang [Japan, Kazakhstan, Korea, Kyrgyzstan, Nepal, Pakistan, Russia, Tajikistan, Turkmenistan, Uzbekistan; Africa, W Asia, Europe].