Russia Flora: Plant, up to 70 (90) cm tall, without basal leaves, usually with root suckers, with long, repeatedly branched, cord-like, mostly horizontal roots. Root crown vertical, slightly sinuous, in upper part up to 5-6 mm in diameter. Stems solitary, almost glabrous. Cauline leaves 2, sessile, opposite, three-parted, their lobes usually 7-8 cm long, 2-2.5(3) cm wide, oblong, entire-margined in lower half, incised-dentate in upper part. Inflorescence loose, up to 50(60) cm long, consisting of successively dichotomously branching lateral branches (flower on first order axis is initiated but does not develop). Bracts with two leaves, similar but with smaller and less divided leaflets. Flowers 2-2.5 cm in diameter. Perianth segments 5(6), 5-7 mm wide, elliptical, white or sometimes slightly reddish outside. Nutlets 7-8 mm long, ovoid, glabrous, slightly convex laterally, bordered along dorsal and ventral sides by relatively wide, roll-like projection; style conical, blunt, not clinging, easily breaking off. 2n = 14 (Probatova, Sokolovskaya, 1989), 28 (Starodubtsev, 1983), 32 (Sokolovskaya, 1966). (Table VII).

Distribution: Okhotsk, Aldan, Kamchatka (southern), Northern Sakhalin, Upper Zeya, Lower Zeya, Bureya, Amgun, Ussuri, Southern Sakhalin, Southern Kuriles (Fig. 20). - Floodplain meadows and riverside shrub thickets, sandy-silty riverbanks, dried-up oxbow lakes and moist shores of water bodies, on dirt road edges, sometimes along railway embankments. VI-VII. - General distribution: European part, Western and Eastern Siberia; Mongolia, Japanese-Chinese. - Described from Kamchatka Peninsula (type - UPS?).