Comarum palustre (syn. Potentilla palustris), known by the common names purple marshlocks, swamp cinquefoil and marsh cinquefoil, is a common waterside shrub. It has a circumboreal distribution, occurring throughout North America, Europe, and Asia, particularly the northern regions. It is most commonly found on lake shores, marshy riversides and stream margins, often partly submerged with foliage floating. It is a parent of some Fragaria, Comarum hybrids, ornamental plants produced by crossing with strawberries.