Formerly part of the Potentilla genus, the Comarum have more recently formed their own genus of which Marsh Cinquefoil is now a member. It bears some similarities to Wood and Water Avens (Geum), also in the Rose family. Its creeping underground stems wind through bogs and soggy moorland round most of Scotland.
The stems are erect and widely branched, with short-stalked leaves which are five-fingered, though sometimes 3 or 7, with oblong leaflets. Each leaflet has pointed teeth with red tips. The stems and leaves are slightly hairy, and the undersides of the leaves are bluish or grey-green.
Flower stalks emerge out of the branch nodes, often with a bract hiding the budding stalk as it grows. Stalks will branch again producing 2 or 3 flowers. The buds begin green and rose-bud like, but turn a deep magenta before opening. The 5 sepals open to reveal the flower, but dominate as they are much longer than the petals, and rounded with pointed tips. Petals are also deep purple-red like the sepals but very narrow, only three-quarters the length of the sepals. There are 12 stamens with deep red filaments and dark purple, almost black anthers. The gynoecium is a spongy mound of many pistils, which develops into something resembling a strawberry. Bees, hoverflies and insects of all kinds love the nectar produced by this flower.