Yellow marsh marigold (Caltha palustris var. palustris), also called common marsh marigold, is found throughout Minnesota except for the southwest corner of the state. It almost always occurs in wetlands. It is found in full or partial sun in woodlands and on meadows, marshes, and streambanks. The large, showy, yellow flowers appear in April and May.

Photo by Kirk Nelson

http://www.minnesotaseasons.com/Plants/yellow_marsh_marigold.html