No, this small Mallow does not grow in marshes. The Rough Marsh-Mallow (Althaea hirsuta) prefers dry meadows on poor soil. It is small and unconspicuous compared to the larger flowers that surround it.
All mallows have below the pink petals a calyx that sits on a kind of deep dish with star-shaped points. The Rough Marsh-mallow has straight hairs on its stem.Difficult to believe that this tiny plant belongs to the same family as the lime tree. But the red and black firebugs know, they prefer to feed on all kinds of Malvaceae.