Russia Flora: Plant up to 40(60) cm tall, with short rhizome and a bundle of adventitious roots. Shoots erect, ascending or creeping, and then rooting at nodes, simple or branched in upper part, less often at base. Stem straight, rarely genicularly bent, up to 0.8(1) cm thick, slightly ribbed, solid or hollow. Basal leaves 5-30 cm long and wide, cordate-reniform, reniform or rounded, with crenate-dentate margins, wavy or almost entire, on petioles up to 20 cm long, about 0.5 cm thick. Young leaves purple-green underneath. Stem leaves and bracts sessile or on short petioles. Inflorescence of 2-8 flowers, loose, sometimes almost corymbiform. Flowers up to 3(3.5) cm in diameter. Perianth segments 5-7, obovate or broadly elliptical, bright yellow, less often orange-yellow. Pedicels 1-5 cm long, slightly elongating in fruit. Stamens 0.5-1 cm long. Leaves up to 15 mm long, arranged star-like in groups of 4-12; style more or less curved, up to 4 mm long. 2n = 28 (Probatova, Sokolovskaya, 1981), 34 (Veselukhina, 1976), 56 (Sokolovskaya, 1963 - as C. sibirica var. nutans Tolm.), 64 (Zhukova, Petrovsky, 1976), 70 (Sokolovskaya, 1960).

Distribution: Chukotka, Anadyr, Anadyr-Penzhina, Koryak, Kolyma, Okhotsk, Aldan, Dauria, Kamchatka, Commander Islands, Northern Sakhalin, Northern Kuriles, Upper Zeya, Lower Zeya, Bureya, Amgun, Ussuri, Southern Sakhalin, Southern Kuriles (Fig. 1). - In swamps, waterlogged meadows, deciduous and mixed forests, along shores of lakes, rivers and streams, from coastal areas to alpine mountain zones. IV-VIII. - General distribution: European part, Caucasus, Western and Eastern Siberia, Central Asia; Scandinavia, Atlantic and Central Europe, Mediterranean, Asia Minor, Dzungaria-Kashgar, Mongolia, Tibet, Japanese-Chinese, North America. - Described from Europe.

Note: A highly polymorphic species representing a complex of forms that vary greatly in genotype, external appearance, structure and size of leaves, flower parts and fruits. In the Russian Far East, 4 subspecies are more or less clearly distinguished:

subsp. sibirica (Regel) Hult. with prostrate, often rooting at nodes shoots, rarely erect; leaf blades rounded-reniform, up to 10(15) cm wide, flowers up to 2(3) cm in diameter; leaves 8-15 mm long, mostly spreading star-like; style up to 4 mm long (almost all Russian Far East);
subsp. nymphaeifolia Worosch. et Gorovoi with erect shoots, ovate or rounded-elliptical leaf blades up to 5(8) cm wide; flowers up to 1.5(2) cm in diameter; leaves crowded, 4-7 mm long; style about 1.5 mm long (Ussuri: south);
subsp. renifolia (Tolm.) A. Luferov with large erect or prostrate shoots up to 40(60) cm tall, reniform leaf blades up to 30 cm wide; flowers up to 3.5 cm in diameter; leaves 9-12 mm long, more or less spreading; style up to 3 mm long (Kamchatka, Commander Islands);
subsp. violacea (Khokhr.) A. Luferov with mostly erect shoots up to 15(25) cm tall and almost corymbiform inflorescence. Lower side of leaves, perianth segments and fruits with more or less intense violet coloration, often as spots. Leaves 12-30, 10-15 mm long; style up to 2.5 mm long (Chukotka: western, eastern, southern; Anadyr, Anadyr-Penzhina, Koryak, Kolyma, Okhotsk: northern).

Russia Flora: from C. caespitosa Schipcz.

Plant, up to 8 cm tall. Stem thin, 1-2 mm thick, more or less sinuous, unbranched. Leaves numbering 2-4; blade up to 1 cm long and 1.2 cm wide, spatulate or rounded-rhombic, with entire margins or slightly notched along the edge. Petiole up to 4 cm long. Flowers solitary, 0.6-1.2 cm in diameter. Perianth segments up to 6 mm long, elliptical, sulfur-yellow, early deciduous. Stamens up to 2.5 (3) mm long. Leaves numbering 3-7, up to 3 mm long, gradually tapering into a style about 0.5 mm long. 2n = 52 (Zhukova, 1968), 56 (Zhukova, Petrovsky, 1972), 560 (Zhukova, Petrovsky, 1971). 

Distribution: Chukotka (western), Anadyr, Kolyma (Fig. 1). - Found in tundra, on silty-sandy shoals, pebble beaches, along water bodies, usually among moss cover. Flowering period V-VIII. - General distribution: Western (northern) and Eastern Siberia. - Described from Siberia.

Note: In swamps, along the edges of water bodies, in hollow depressions, form f. natans Tolm. occurs, which is characterized by prostrate shoots that root at the nodes with strongly elongated internodes.

Russia Flora: Plant, up to 8(10) cm tall. Stem prostrate, arcuately curved, less often erect, unbranched. Leaves numbering 2-5; blade 0.5-2(4) cm long and wide, rounded-reniform or rounded, with entire margins or slightly wavy along the edge, with a purple tinge on the lower side. Petiole up to 7 cm long. Flowers solitary, less often grouped in 2-3, up to 1.5(2) cm in diameter. Perianth segments up to 8(10) mm long, rounded-elliptical, bright yellow, often purple underneath. Stamens up to 5 mm long. Leaves numbering 6-10, up to 6 mm long, more or less abruptly transitioning into a curved style up to 1 mm long. 2n = 32 (Zhukova, Petrovsky, 1972), 52 and 56 (Zhukova, 1969), 60 (Zhukova, 1980), 72 (Zhukova, 1968).

Distribution: Chukotka, Anadyr, Anadyr-Penzhina, Koryak, Kolyma, Aldan, Kamchatka (western, eastern), Commander Islands (Fig. 1). - Found in tundra, along water bodies, in swamps, on hummocks and in hollow depressions, on mountain balds, near snow patches. Flowering period V-VIII. - General distribution: European part (Arctic), Western (northern) and Eastern Siberia; Scandinavia, North America. - Described from North America.