Herbs, annual, biennial, or perennial [rarely shrublets or shrubs]. Leaves simple, usually palmately divided or cleft, sometimes entire or pinnately lobed, petiolate. Basal leaves usually forming a rosette. Cauline leaves opposite or alternate. Inflorescence terminal or axillary, cymose, bracteate. Flowers usually paired or occasionally solitary, actinomorphic, rarely somewhat zygomorphic. Sepals 5, imbricate, apex obtuse to caudate. Petals 5, distinct, sometimes clawed, apex rounded, retuse, or emarginate. Stamens 10, in 2 whorls, outer ones opposite to petals, inner ones alternating with petals, all with anthers or very rarely (in G. pusillum) 5 reduced to staminodes. Nectaries usually 5 and alternate with petals, rarely (in G. sinense) united into a ring. Ovary 5-locular, with 2 superposed ovules per locule; style distinctly 5-cleft. Fruit a schizocarp, long beaked, splitting into 5 1-seeded mericarps.

Primary leaf blade divisions are named segments and second ones lobes. The middle segment is measured from leaf blade apex to the insertion of the petiole with the leaf blade. The main sinus is measured from the leaf blade apex to the junction between the middle segment and the adjacent lateral segments. The second sinus is the deeper of the middle segment. Sepal length does not include mucro length. Fruit length is measured from the mericarp base to the apex of the stigmatic remains. The fruit rostrum length is measured from the mericarp apex to the base of the stigmatic remains including, when present, a narrowed apical part.

Five species recorded from China are of uncertain identity or are too poorly known to be treated here and are discussed unnumbered at the end of the generic treatment.

Geranium schrenkianum Trautvetter (Bull. Soc. Imp. Naturalistes Moscou 57: 53. 1882) is widespread in Kazakhstan and is expected to be found in Xinjiang. This species is a small annual, easily recognized by its palmately divided leaves, petals 3-4 mm with emarginate apex, and antrorsely appressed trichomes on stem, petioles, peduncle, and pedicels.

Species incertae sedis

The following species have been described from Chinese material, or recorded in China, but are imperfectly known as no specimens have been seen.

Geranium camaense C. C. Huang in S. Y. Jin, Cat. Type Spec. Herb. China, 301. 1994.

This species is only known from the type collected in Xizang (Dinggyê Xian) at ca. 4000 m. According to the original description, this species is similar to Geranium lucidum Linnaeus but differs in having leaves and flowers glabrous. Geranium lucidum is a European species that reaches the W Himalayas and Nepal. It is an annual and very easy to recognize by its calyx with lengthwise keels and transverse flaps between these. Unfortunately, it has not been possible to examine the type specimen of G. camaense.

Geranium platyrenifolium Z. M. Tan, Bull. Bot. Res., Harbin 6(2): 52. 1986.

Geranium tanii Aedo & Muñoz Garmendia; G. trifoliatum Z. M. Tan (1994), not Andrews (1805).

According to the original description, this species has roots bearing 1 or 2 tubers at distances up to several cm from their origin, opposite leaves deeply divided, stipules distinct, cymules 2-flowered, petals 1.5-1.8 cm, with rounded base and with trichomes, and indumentum nonglandular. It is found in meadows of SW Sichuan. Unfortunately, it has not been possible to examine any specimens belonging to this species.

Geranium rubifolium Lindley, Edwards’s Bot. Reg. 26: t. 67. 1840.

This species was reported in forests at ca. 2700 m in Xizang (Yadong) by L. R. Xu & C. C. Huang (Fl. Reipubl. Popularis Sin. 43(1): 72. 1998). This area is on the S side of the Himalayas between India (Sikkim) and Bhutan, but the species was previously considered endemic from N Pakistan and Kashmir far to the West. This Chinese report mentioned the plant as having petals with a basal spot. This feature does match Geranium rubifolium, which has uniform petals, and would correspond to G. procurrens Yeo (Bot. Mag. 179: t. 644. 1973), a species widespread in the Himalayas but not recorded from China. Unfortunately, it has not been possible to examine the specimen reported from China.

Geranium solitarium Z. M. Tan, Acta Phytotax. Sin. 33: 608. 1995.

According to the original description, this species has roots long and thickened, opposite leaves not deeply divided, stipules distinct, cymules 1-flowered, petals ca. 1.8 cm, with rounded apex and basally with trichomes, and indumentum nonglandular. The fruit and seed are unknown. It is found in alpine habitats of N Sichuan. Unfortunately, it has not been possible to examine any specimens belonging to this species.

Geranium yaanense Z. M. Tan, Acta Phytotax. Sin. 33: 611. 1995.

According to the original description, this species has opposite leaves not deeply divided, stipules distinct, cymules 2-flowered, petals ca. 9 mm, with rounded apex and basally with trichomes, and indumentum glandular. It has been considered a synonym of Geranium moupinense. However, the latter has alternate leaves and reticulate mericarps. Unfortunately, it has not been possible to examine any specimens belonging to this species.

About 380 species: cosmopolitan, especially in temperate and tropical mountains; 50 species (18 endemic, three introduced) in China.