Small Flowered Cranesbill

Foodplant / parasite
mainly epiphyllous, becoming superficial pseudothecium of Coleroa circinans parasitises live leaf of Geranium pusillum
Remarks: season: 10-4

Foodplant / open feeder
Limobius borealis grazes on leaf of Geranium pusillum

In Great Britain and/or Ireland:
Foodplant / parasite
sporangium of Peronospora conglomerata parasitises live Geranium pusillum
Other: major host/prey

Foodplant / parasite
cleistothecium of Podosphaera fugax parasitises live Geranium pusillum

Foodplant / spot causer
hypophyllous colony of Ramularia anamorph of Ramularia geranii causes spots on live leaf of Geranium pusillum

Foodplant / parasite
hypophyllous telium of Uromyces geranii parasitises live leaf of Geranium pusillum

Although found as a naturalized weed in Taiwan, this species could be found as a native plant near the W boundaries of China, because its natural area includes the W Himalayas. This species also grows as an introduced weed in America and Australia.

A diffuse slender glandular-pubescent annual. Leaves suborbicular or reniform, 10-28 mm broad, plamatipartite; segments 5-7, terminally 2-3-lobed, lobes obtuse, mucronate. Stipules 1.5-2 mm long, ovate-lanceolate, sometimes 2-fid, hairy. Peduncles 2-flowered, glandular. Flowers c. 4 mm broad. Bracts ovate-lanceolate, 1-1.5 mm long, hairy. Sepals 1.5-3 mm long, ovate or oblong-ovate, long ciliate, glandular-pubescent. Petals slightly exceeding sepals, obovate, lilac or pink, base sparsely ciliate. Filament base dilated, ciliate. Beak 6-8 mm long, glandular-pubescent. Mericarps appressed pubescent, not wrinkled. Seed c. 1.5 mm long, oblong, glabrous.

Annuals. Stem 10-50 cm tall, erect or decumbent, not rooting at nodes, with 0.1-0.3 mm patent nonglandular trichomes and 0.1-0.2 mm patent glandular trichomes. Stipules lanceolate, distinct. Leaves opposite; petiole with 0.1-0.3 mm patent nonglandular trichomes and 0.1-0.2 mm patent glandular trichomes; leaf blade 1.5-3.8 cm, palmately cleft, ratio of main sinus/middle segment length = 0.3-0.75, pilose with appressed nonglandular trichomes; segments 5, obtriangular, 2-4 mm wide at base, 3(-5)-lobed at apex, ratio of second sinus/middle segment length = 0.16-0.29. Cymules solitary, 2-flowered; peduncle 0.5-3.2 cm. Pedicel 0.6-1.6 cm, with 0.1-0.3 mm patent nonglandular trichomes and 0.1-0.2 mm patent glandular trichomes; bracteoles linear-lanceolate. Sepals 3-4.5 mm, mucro ca. 0.1 mm, ratio of mucro/sepal length = 0.02-0.03, outside with 0.6-1 mm patent nonglandular trichomes and 0.2-0.5 mm ± patent nonglandular and glandular trichomes, outside glabrous. Petals pale purple, 2-3 mm, erect to patent, both surfaces glabrous, margin basally ciliate, apex emarginate with a 0.2-0.5 mm notch. Stamens external whorl lacking anthers and reduced to 5 staminodes; filaments white, lanceolate, abaxially pilose and proximal half ciliate, trichomes 0.1-0.2 mm; anthers purplish, ca. 0.3 mm. Nectaries 5, hemispheric, glabrous. Stigma yellowish. Fruit 0.9-1.1 cm, erect when immature; mericarps smooth, without a basal callus, with to 0.2 mm appressed nonglandular trichomes, base with a few cilia; rostrum 7-9 mm, without a narrowed apex; stigmatic remains 0.5-0.7 mm. Seeds 1.7-1.8 mm. Fl. Jun-Jul, fr. Aug-Oct. 2n = 26.

Distribution: Europe (except N.), W. & C. Asia, Africa, Syria and W. temperate Himalaya, from 800-2700 m.

Naturalized in Taiwan [native to Afghanistan, W Asia, Europe, Kashmir, Kazakhstan, Kyrgyzstan, Russia, Tajikistan, Turkmenistan, Uzbekistan].

Fl. Per.: April-May.

Open habitats, dry grassland, cultivated and waste places; 1800-2300 m.

Geranium pusillum Burm. f. Sp. Geran. 27. 1759 Annual or biennial. Stems branched at the base, the branches decumbent or prostrate, 1-5.5 dm. long, forking, puberulent; leaf-blades reniform in outline, 1.5-5 cm. broad, 5-7parted, the divisions toothed or lobed at the apex ; petioles puberulent and with few spreading hairs ; pedicels in pairs, minutely glandular-pubescent, especially under the calyx ; sepals elliptic to ovate-elliptic, 2.5—1 mm. long, awnless; petals violet, often pale, cuneate, longer than the sepals, notched ; stamens 5 ; style-column 8-9 mm. long at maturity, shortbeaked ; carpel-bodies about 2 mm. long, finely pubescent; seeds smooth.
Type locality : England and France.
Distribution: Ontario to British Columbia, New England, New Jersey, Virginia, Nebraska, and Utah ; Bermuda. Naturalized from Europe.

Wikimedia Commons has media related to Geranium pusillum.

Geranium pusillum, commonly known as small-flowered crane's-bill or (in North America) small geranium, is a herbaceous annual plant of the genus Geranium.

Small geranium is native to Europe but is introduced in almost every region of the USA and Canada, where it is associated with ecologically disturbed sites.