Twin-flowered Marshmarigold, Broad-leaved Marshmarigold, White Marshmarigold: Caltha leptosepala ssp. howellii (formerly Caltha biflora) - 1-2 flowers are found on the stems. The leaves are about as wide as long.
Elkslip Marsh Marigold: Caltha leptosepala ssp. leptosepala (Synonyms: Caltha biflora var. rotundifolia, Caltha chelidonii, Caltha leptosepala ssp. leptosepala var. leptosepala, Caltha leptosepala var. rotundifolia, Psychrophila leptosepala) - 1 flower is typically found per stem. The leaves are longer than wide.
Western Marshmarigold, Yellow Marshmarigold: Caltha palustris -