Boltonia decurrens General Summary
Boltonia decurrens, a member of the Asteraceae, is a floodplain perennial endemic to the Illinois River Valley. The species was originally classified as Boltonia asteroides (L.) L'her var. decurrens Engelm., being differentiated from other varieties by leaves which are decurrent. It was not until 1985 that it was recognized as a distinct species due to the decurrent leaves and lack of rhizomes. A mature B. decurrens plant is 1.5 m to 2 m tall and flowers during the period from August to October.
Historically, populations of Boltonia decurrens were contiguous along a 400 km range from LaSalle, Illinois to St. Louis, Missouri on the Mississippi River. The number of naturally occurring populations, which fluctuates annually, continues to show a net decline. Approximately 20 disjunt populations currently range from Bureau County, IL south to St. Clair County, IL and west to St. Charles County, MO. In 1988, the United States Fish and Wildlife Service placed B. decurrens on the Federal List of Threatened Species. It is currently listed as endagered in Missouri and threatened in Illinois.
Plant populations have been reduced due to habitat destruction and modification. Construction of dams, locks and levees long the river has altered the natural hydrologic cycle, causing either prolonged inundation of flood waters or a lack of flooding. Many wetland areas have also been drained for agricultural purposes. Extant populations have become isolated and reduced to human disturbed, alluvial soil habitats, old fields, roadsides and disturbed bottomland lake shores.
The Boltonia decurrens Research Station at SIUE is directed by Dr. Marian Smith. Dr. Smith has been teaching at SIUE since 1987 and has concentrated her research efforts on B. decurrens since approximately 1989. Her research lab usually includes more than 10 working students at any given time. Enabling undergraduates to gain research experience is a priority. Research projects range from plant demography and herbivory to physiology and genetics. Although B. decurrens is a valuable native plant species in and of itself, its value could be considered to be even greater as an indicator species. The rarity of B. decurrens should initiate concern for the rarity of the habitat which it requires and of other species which require the same conditions. Effective habitat conservation and management should be based on extensive scientific research; understanding the population dynamics and demography of native species should be essential to management plans.
Boltonia decurrens Site Distribution Map
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