Caltha palustris L.

Caltha palustris L.. Caltha palustris, known as marsh-marigold and kingcup, is a small to medium sized perennial herbaceous plant of the buttercup family, native to marshes, fens, ditches and wet woodland in temperate regions of the Northern Hemisphere. It flowers between April and August, dependent on altitude and latitude, but occasional flowers may occur at other times.