Marsh-marigold - Caltha palustris
The Marsh-marigold is also known as Kingcup. It is in fact not a marigold at all, but a member of the family, which includes buttercups and anemones.

Habitats
It grows in a variety of neutral to base-rich wet habitats including fens, marshes, riversides, wet woodlands and ditches. It is believed that the Marsh-marigold is one of Britain’s most ancient native plants as it is thought to have been growing here before the last Ice Age. Once the ice retreated it spread across Britain where it did well in the damp conditions.
Description
Large bright yellow buttercup-like flowers with five petals make the Marsh-marigold easily identifiable. Flowers often appear as early as March, lasting until May and so it is often thought of as a herald of spring. Its leaves are bright green, glossy and heart shaped about 10cm wide and held above water on long-stalked, smooth and hollow stems.
Threats
The population of Marsh-marigold has remained fairly constant in Wiltshire, although individual populations are often small. It underwent a slight decline in the 1970’s when there were agricultural grants for draining wetland to use for farming. Once these grants were removed its numbers recovered and it is now thought to be stable.
Conservation
Being generally protected by the Wildlife & Countryside Act 1981 it is an offence to uproot Marsh-marigold without a landowner’s consent.