Michaux's Sumac - Rhus michauxii
Contributed by Charlie Williams, member Mecklenburg County Parks and Recreation, Stewardship Advisory Council
Michaux’s sumac Rhus michauxii is a low-growing shrub listed by the US fish and Wildlife Service as a federally endangered species on September 28, 1989. Other common names are dwarf sumac or false poison sumac. Historically, the plant was known to occur in the inner Coastal Plain and Piedmont of the Carolinas, Florida and Georgia.
The species was both discovered by and named for French explorer-botanist André Michaux (1746-1802). This is rather unusual. However, nearly a hundred years after Michaux published his name for the plant, botanist C.S. Sargent discovered that Michaux's name, Rhus pumila, had already been used for another plant. This invalidated Michaux's name so Sargent chose to honor the plant's discoverer with the new name Rhus michauxii.
Michaux worked for the French government as a researcher and plant collector. From a garden near Charleston he used as a base, Michaux traveled widely and often, especially in the Carolinas and Georgia. He was the first to document many plants in our flora. Dr. David Rembert of USC did a study of Michaux's work and credits the French botanist with being the first to name 283 species found in the Carolinas. Traveling throughout eastern North America, he also named many other species not found in the Carolinas.
Exactly where and when André Michaux may have discovered the rare sumac that bears his name will be the subject of one of the more than thirty presentations to be given at the upcoming ANDRE MICHAUX INTERNATIONAL SYMPOSIUM in May. Belmont Abbey College, Daniel Stowe Botanical Garden and the Gaston Day School are hosts for this event being held from May 15-19 in Gaston County, NC (near Charlotte). There is a website atwww.michaux.org.
Michaux’s sumac is a dioecious shrub; single plants are not both sexes as are most plants, but each plant is a single sex. The species has been seriously impacted by habitat fragmentation and habitat loss. The most recent reports indicate that there are 36 known populations, but a population of this rhizomatus shrub may have just one genetic individual with clonal reproduction only. Most of the known populations are found in NC; Kershaw County is the only SC location listed in the Manual of the Vascular Flora of the Carolinas (1968). The plant is quite rare throughout its range.
Individual plants are reported to grow to a height of about a half-meter. The plant is deciduous with alternate, pinnately compound leaves. Each compound leaf has between 7 and 13 oblong, toothed leaflets. Sometimes the rachis will be narrowly winged near the apex. In addition to the dwarf size of this sumac, another conspicuous feature is that all parts of the plant are densely pubescent. The greenish-yellow insect-pollinated flowers are individually tiny, but borne in terminal clusters containing many small flowers. The clusters of ripe fruits are red.
The species is shade-intolerant and dependent on some kind of disturbance to maintain the open condition of its habitat. The plant cannot survive if the canopy closes over it. Make a note, then, of the discovery in recent years of the largest known population of Michaux’s sumac. It is on the Fort Pickett military reservation in the Virginia Piedmont. In the context of training to fight wars, “disturbance” takes on new shades of meaning. At Fort Pickett and wherever soldiers are trained for combat, of course the word “fire” is a verb as well as a noun. When soldiers train, they “fire” artillery and other weapons and these weapons sometimes start a “fire” as well as “clear openings” in the canopy at the point the shell or other ordnance impacts. Botanists have known for some time about the role that long-term fire suppression has played in the decline of many species including Michaux’s sumac. However, the Fort Pickett population, is an unusual case because frequent, intense, man-made fires from military activities have helped an endangered species.
Efforts have been made to re-introduce the species to locales where it has been extirpated. In Mecklenburg County, NC the Conservation Biology Laboratory at UNC-Charlotte has been working in cooperation with the Mecklenburg Park and Recreation Department to restore Piedmont prairies within nature preserves in county the park system for several years. Early travelers described extensive wild and fertile prairies across the Carolinas Piedmont, but this habitat type had been all but destroyed by agriculture and fire suppression during the last two centuries. Many Schweinitz's sunflowers, another globally endangered species, have been rescued from road widening projects and planted in these restored prairies. The sunflowers are thriving. Last November, to the delight of conservationists, 29 rescued Michaux's sumac were also planted in two restored Piedmont prairies in Mecklenburg parks. The last reliable sighting of Michaux's sumac in Mecklenburg County had occurred 207 years earlier, by Michaux himself!