A member of the rose family, Comarum palustre is an herb of wet places in the lowlands to the subalpine zone, sometimes found emergent from standing water with deep red wine-colored flowers. Plants grow from a woody rhizome, stems 30- 60 cm tall. There are both basal leaves and broadly spaced alternate stem leaves. The leaves are palmately divided into five segments (upper stem leaves in 3), with long petioles. Each segment is elliptic, often slightly broader at the tip than the base, and serrate in the upper half or two-thirds. Leaves are 2-8 cm long and have stipules at the base that sheathe the stem. Leaves are dark green above and paler below. At the top of the stem, plants produce a few blossoms. Both petals and sepals number five and are red-purple tinged. The sepals are large (appearing to be the petals), 7-15 mm long, glandular hairy on the backs, the petals are much smaller. The numerous separate carpels with straight red styles form a thimble-shaped structure at the center of the flower. Inside the flower there are circa 20 stamens, with stout red filaments and black-purplish anthers. The fruit is a cluster of many fleshy achenes, looking like raspberries. It's hard to mistake purple marshlocks for any other species ­ this is the only wetland species with deep red flowers and palmately divided leaves that occurs in Denali .

Marsh cinquefoil is a perennial that flowers in early to mid-summer. The flowers are protandrous-the stamens release pollen before the stigma of the same flower is receptive. The inflorescence elongates as the fruit matures.

Flowers of marsh cinquefoil are nectar-producing and visited by a variety of insects, including butterflies, bumblebees and wasps. Plants can be self-fertilized, but seed set is increased with out-crossing (Olesen and Warncke 1992). Also, marsh cinquefoil spreads clonally, growing from its rhizome.

The species prefers soils rich in organic material, but can also grow in neutral soils (Macek and Leps 2008).

Wet to aquatic sites.