Swamp rose-mallow (Hibiscus moscheutos) COSEWIC assessment and status report: chapter 9
Special Significance of the Species
During the 1900s, Hibiscus moscheutos was investigated as a fiber source, particularly in New Jersey. Like ramie, the perennial plants could be cut annually, however the extracted fibre apparently lacked sufficient strength for commercial use. No food use is known, but the seeds of H. moscheutos are reported to be of use medicinally for their cordial, stomachic, nervine, pungent, demulcent, and emollient properties (Winters, 1970). The most important economic use the rose-mallows generally, is as ornamentals (Winters, 1970). Since the early 1900s, successful hybridization of H. moscheutos with the progeny of H. coccineus, H. laevis, and H. grandiflorus has produced several widely-used F1 hybrids – notably Southern Belle and Dixie Belle. These hybrids are available as seed from catalogue companies and are appropriate for USDA zones 5 to 10. The hybrid found for years in the nursery trade as Meehan’s Mallow Marvels, was obtained by crossing a hardy red-flowered hybrid of H. coccineus X H. militaris with H. moscheutos (Wise and Menzel, 1971; Bailey, 1949; Jury, 1978). Native plants are also valued as ornamentals and have been transplanted into gardens in Belle River, Walpole Island, Amherstburg, and Shrewsbury.
Cahoon and Stevenson (1986) studied rates of production, leaf grazing, and stem decomposition associated with H. moscheutos at a brackish marsh of Chesapeake Bay, where it dominates over one hectare, and contrasted this with other fresh and saltwater species. The decomposition rate of Hibiscus stem material was estimated to be on the order of 7 to 8 years, or up to five times slower than stems of other typical brackish marsh species (Typha, Scirpus, and Phragmites). Hibiscus stem tissue stands upright long after dying due to its high lignin content. Once it has fallen, it decomposes slowly due to lack of submergence, which may limit the development of fungal microflora and degadative enzyme production (Gessner, 1980, cited in Cahoon and Stevenson, 1986). They found that most of the net community productivity may end up accumulating in the sediment horizon in the Hibiscus marsh, with only Scirpus fluviatilis coming close to the abnormally high rates of accretion (>1cm/yr) found in Hibiscus. They hypothesized that Hibiscus differs from Spartina in salt marsh systems by nourishing a more robust grazing food chain and by not exporting significant quantities of detrital material to surrounding coastal waters. They suggested that the accumulation within Hibiscus marshes may be important in the Chesapeake region, where apparent sea level rise is 4 mm/year and some irregularly flooded marshes are eroding due to low rates of sediment accretion.
Hibiscus moscheutos can occur in fairly high numbers in the marshes of southwestern Ontario, where it contributes to their aesthetics. In association with Typha and Scirpus spp., rose-mallow may also play a role in shoreline stabilization and the creation of wildlife habitat.
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