• Scientific Name: Caltha palustris Linnaeus
• Ref: Sp. Pl. 1: 558. 1753.
• English Common Name: marsh-marigold, kingcup
• Chinese Common Name: 驴蹄草 lǘtícǎo
• Family: Ranunculaceae
• Genus: Caltha
• Distribution: Mountain regions, grassy slopes, valleys, marshlands, forests, by streams, in water; 600–4000 m. S and SW Gansu, Guizhou, Hebei, Heilongjiang, W Henan, Jilin, Liaoning, Nei Mongol, Shanxi, Sichuan, Xinjiang, E and SE Xizang, C and NW Yunnan, Zhejiang [most temperate regions of N hemisphere].

Plants with numerous fleshy roots. Stems 10--120 cm tall at fruiting, (1.5--)3--12 mm in diam., branched, rarely simple, basal leaves 3--7, long petiolate; petiole (4--)7--24 cm; leaf blade orbicular to orbicular-reniform or cordate, (1.2--)2.5--5 × (2--)3--9 cm, base deeply cordate, margin densely denticulate, apex rounded. Cauline leaves usually diminishing upward, rarely equal to basal leaves in size, orbicular-reniform or triangular-cordate, shortly petiolate or uppermost ones sessile. Monochasium often solitary, (2 or)3--5-flowered; pedicels more than 1.5 cm at fruiting. Flowers 2--3 cm in diam. Sepals 5, yellow, obovate to narrowly obovate, 1--1.8(--2.5) × 0.6--1.2(--1.5) cm, apex rounded. Stamens 4.5--7(--9) mm; anthers sessile, oblong, 1--1.6 mm. Follicles (5--)7--25, ca. 1 cm × 3 mm; persistent style 1--3 mm. Seeds black, rarely pale greenish brown, narrowly ovoid, 1.5--2 mm. Fl. May--Sep. 2n = 16, 32, 55--57, 60, 64, 80. (Flora of China)