Caltha L.
Fls few to 1, perfect, regular, hypog. Sepals 5-10, petaloid, yellow or white; petals 0; stamens ∞; carpels 5-11, ovules several in 2 series. Fruit of a few follicles, each with several to many seeds. Perennial herbs with creeping rhizomes and ± cordate radical lvs. About 20 spp. of temperate regions. The N.Z. spp. are endemic and belong to the section Psychrophila as defined by Hill (Ann. Bot., Lond. 32, 1918, 421-422).