The huge, showy blossoms of Swamp Rose Mallow (Hibiscus moscheutos), a member of the Mallow (Malvaceae) family, begin to appear in mid-summer, and continue into early fall. The flowers are most often pink
or white, sometimes with a red throat, inspiring a different common name, Crimsoneyed Rose Mallow.
But deeper shades of pink and even red are possible.
Insects like the Eastern Tiger Swallowtail in the photo above are enticed to visit Swamp Rose Mallow’s flowers for the nectar accessible through slits at the base of the flower.
In addition to seeking nectar, bees visit to harvest the abundant pollen the flowers offer. Bees eat pollen, and female bees gather it to provision their nests with this nutritious food for their larvae. The Rose Mallow Bee (Ptilothrix bombiformis) is a specialist forager that only eats the pollen of plants in this genus (Hibiscus) and one other, Morning Glories (Ipomoea).
Numerous stamens (the male reproductive parts) form a tube that encircles the pistils (female reproductive parts). Each stamen is topped by an anther that releases pollen. At the tips of the pistils are the stigmas, the receptive part of the pistil where the pollen must be deposited in order to initiate pollination. The stigmas extend significantly beyond the stamens, separating them from the flower’s own pollen, thus decreasing the chances that the flower will be self-pollinated.
Bees are thought to be the primary pollinators of Swamp Rose Mallow, in spite of the fact that they devour vast quantities of its pollen. It also seems plausible that large butterflies such as the Eastern Tiger Swallowtail are effective pollinators of Swamp Rose Mallow. Butterflies visit the flowers purely for nectar; they have no interest in consuming pollen. Butterflies head for the nectaries, accessed through slits at the throat of the flower. As the butterflies drink, their bodies brush against the anthers, picking up pollen. When the butterfly moves on to a different flower, some of that pollen may adhere to the stigmas of the new flower, triggering pollination.
There isn’t much waste in nature. Bees even scavenge pollen that has fallen onto the flower petals. Beetles join the bees at this pollen feast. Hibiscus Seed Beetles (Althaeus hibisci) are primarily interested in eating the seeds of Swamp Rose Mallow and other related species, but while they wait for the seeds to become available, they also consume pollen. As an additional benefit, cruising the flowers is an effective way for the beetles to hook up with members of the opposite sex!
Swamp Rose Mallow benefits butterflies in other ways. It is a potential food plant for the caterpillars of several butterflies, including the Gray Hairstreak, Common Checkered-skipper, and Painted Lady.
Birds also benefit from the presence of Swamp Rose Mallow. Red-winged Blackbirds may use it as a nesting site.
Swamp Rose Mallow’s seeds are a fall and winter source of food for birds,
including Northern Pintails, Wood Ducks and Blue-winged Teal.
Swamp Rose Mallow is native from Ontario, New York and Massachusetts in the north, south to the southeastern and south central United States. It can grow to a height of about 6.5 feet (2 meters). Swamp Rose Mallow’s natural habitats are primarily wetlands, including swamps, marshes
and wet meadows.
Cech, Rick; Tudor, Guy. Butterflies of the East Coast. 2005.
Rhoads, Ann Fowler; Block, Timothy A. The Plants of Pennsylvania. 2007
Willmer, Pat. Pollination and Floral Ecology. 2011
Shimamura, Ryouji; Kachi, Naoki; Kudoh, Hiroshi; Whigham, Dennis F. Visitation of a specialist pollen feeder Althaeus hibisci Olivier (Coleoptera: Bruchidae) to flowers of Hibiscus moscheutos L. (Malvaceae). 2004.
Klips, Robert A.; Sweeney, Patricia M.; Bauman, Elisabeth K. F.; Snow, Allison A. Temporal and Geographic Variation in Predispersal Seed Predation on Hibiscus moscheutos L. (Malvaceae) in Ohio and Maryland, USA. 2005.
Mary Anne, I just found The Natural Web last night…I’m blown away by the photographs and deep knowledge, but knowledge presented in such a away that non-scientists like me can understand! I love to spread the word about the importance of incorporating as many natives in our gardens as possible. However in our very imperfect nursery world, native species can be very hard to find. And sometimes cultivars/nativars can do the job but sometimes they can’t’. In the case of these beauties there are cultivars of the species and I have some friends who have huge swamp rose mallows that look much more spectacular than those seen in the wild. I’m planning on planting these this spring. My question, and one that I hope you can address(and maybe you do,as I said I just found you last night) is in the case of our native mallow is a cultivar effective for all the feeders you mentioned above?( keeping in mind things like purchase local, no bred for sterile, no double flowers).
Thanks for the kind words, Vernah! There’s a lot we don’t know yet about the value of cultivars in comparison to straight species. Doug Tallamy and others from the University of Delaware have teamed up with the Mt Cuba Center to do some research in this area. So far, it appears that as far as value for pollinators, it depends on the individual cultivar. In terms of insects that eat plants, the color of the plant part consumed is likely to make a big difference, since color reflects the chemical make-up of the plant tissues. I haven’t seen any research specifically about Swamp Rose Mallow cultivars. You could try them and let me know who you observe visiting them! Here is a link to some of the results of the research done at Mt Cuba: http://mtcubacenter.org/research/trial-garden/. I hope this helps a little.
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Why are there so many ants on the blossoms?
Ants seem to be everywhere you look. I can only speculate that they visit the flowers for nectar, and/or in the pursuit of other insects that might be a good source of protein for them.
Another of your outstanding articles with excellent photos. A pleasure to read and from which to learn.
thank you, Mary Anne. I have been noticing these mallows since you pointed them out to our group at the Wildflower preserve. Most recently I have enjoyed their profuse blooming in Pennypack Park and in the Hirschorn Garden in DC. It must be time to add to my native garden in Levittown. The pollen shots are just amazing!!!!! One million sparks of gratitude your way for my continuing education. Yours in the Amazing Outdoors, Patricia Merkel
The blossoms are gorgeous!