any of several plants (genus Hibiscus) of the mallow family, with showy flowers; esp., a marsh species (H. palustris) having large pink, red, or white flowers
See rose mallow in American Heritage Dictionary 4
noun
A tall marsh plant (Hibiscus moscheutos) of eastern North America, having leaves covered with whitish down and large flowers with white, pink, or rose petals with crimson bases.