Last weekend, while exploring the John H. Chafee Nature Preserve in Rhode Island, I encountered a large tropical-looking flower. It seemed out of place in a New England marsh. However, the first specimen I noticed was tucked so far back in the vegetation that there was no way for me to get close enough to identify it. I only knew that it was big and pink. Luckily, slightly further along the edge of the marsh was another patch of this plant that I could gain access to, and I was able to identify it as swamp rose mallow (Hibiscus palustris, although classified by some as Hibiscus moscheutos). The species name “palustris” means “swampy,” referring to this plant’s preference for marshy or wet soil. This is fitting since as an obligate wetland species it will almost always be found in marshes and swamps and along the edges of ponds. Although many of the plants in the Hibiscus genus grow in tropical or semi-tropical regions, several hardier species, such as this one, are native to North America. Swamp rose mallow is native throughout much of the eastern United States, stretching from Massachusetts to Florida and west to the Great Lakes and Texas.
Swamp rose mallow does indeed have large showy flowers (stretching 4 to 7 inches across) with 5 petals, and can range in color from white to pink. In the northern end of its range where we are, pink is the more common variety. In the center of each flower, there are numerous stamens arranged in a column around a single central pistil. Five rounded stigmas emerge from the end of this column. This central stamen column is one of the unifying features of the mallow family. Each individual flower lasts for only one day, but the plant will continue to produce flowers consistently throughout its flowering season (between July and September). Note the different stages of development found among the flowers of a single plant pictured below. The leaves are simple, toothed, heart-shaped, and alternately arranged along the stem.
Central stamen column.
New swamp rose mallow flower bud.
A more developed swamp rose mallow flower bud.
A camouflaged green crab spider (Misumessus sp? perhaps?) at the base of the swamp rose mallow flower.