Geranium hayatanum Ohwi

This species shares with Geranium suzukii the trailing habit and 1-flowered cymules. Both are also endemics from Taiwan. However, G. hayatanum is very easy to recognize by its long petals, its long and connate stipules (similar to those of G. koreanum), and its decumbent but not rooting stems.

Perennials. Rootstock ± horizontal, 3.6-8 mm in diam., not tuberculate, with thickened roots along rootstock. Stem 18-60 cm tall, trailing or ascending, not rooting at nodes, with 0.2-1 mm patent to retrorse nonglandular trichomes. Stipules broadly ovate, connate. Leaves opposite; petiole with 0.3-1 mm patent to retrorse nonglandular trichomes; leaf blade 2.8-7.2 cm, palmately cleft, ratio of main sinus/middle segment length = 0.75-0.92, pilose with appressed nonglandular trichomes; segments 5, rhombic, 3.4-9.8 mm wide at base, 5-11-lobed in distal half, ratio of second sinus/middle segment length = 0.21-0.38. Cymules solitary, 1-flowered; peduncle (0.9-)2.4-7.6(-15.4) cm. Pedicel 1.5-3(-5) cm, with 0.2-0.8 mm patent to retrorse sometimes uncinate nonglandular trichomes; bracteoles lanceolate. Sepals 6.5-10.1 mm, mucro 1.1-2.5 mm, ratio of mucro/sepal length = 0.14-0.24, outside with 0.2-1.4 mm antrorse to patent nonglandular trichomes, inside glabrous. Petals light purplish with a whitish base, (1.2-)1.4-1.8(-2) cm, erect to patent, both surfaces basally with trichomes, margin basally ciliate, apex rounded or rarely emarginate with a 0.2-0.4 mm notch. Staminal filaments purplish distally but paler at base, lanceolate, abaxially pilose and proximal half ciliate, trichomes 0.2-0.6 mm; anthers bluish, 1.7-2.1 mm. Nectaries 5, hemispheric, abaxially glabrous, apex with a tuft of trichomes. Stigma deep pink. Fruit 2.4-3.2 cm, erect when immature; mericarps smooth, with a basal callus, with 0.3-1.2 mm erect to patent nonglandular trichomes; rostrum 1.5-2.3 cm, with a 1.6-3.4 mm narrowed apex; stigmatic remains 3.5-5.6 mm. Seeds 2.3-3.5 mm. Fl. Jul, fr. Aug.

Taiwan.

● Forest floors, rocky slopes, trailsides, exposed scree slopes; 2700-3800 m.

Geranium uniflorum Hayata, J. Coll. Sci. Imp. Univ. Tokyo 25(19): 65. 1908, not Pacho (1827).