Decurrent false aster is a perennial plant that occasionally reaches heights of over 6 feet. It blooms from July to October and bears seeds from August to October. Leaves are linear and narrow and have a blue tint. The lower leaves are broader and larger. This plant is called "decurrent" because the leaf tissue extends down the stem from the point of leaf attachment. The flowers are about the size of a quarter. They occur in branched groups of composite heads with yellow disk flowers and white to purplish or pinkish ray flowers.
Similar species: Decurrent false aster is closely related to Boltonia asteroides var. recognita, which is a common weedy species of false aster or "false starwort." It is sometimes found in the same habitat with decurrent false aster; however, it lacks decurrent leaves.
Height: 1 to 5 feet.
Presently it is known to occur only in St. Charles County.
Habitat and Conservation
Historically, this plant was found in wet prairies, in marshes, and along the shores of some rivers and lakes. Current habitats include riverbanks, old fields, roadsides, mudflats, and lake shores. Conservation methods include wetland protection, low-intensity agriculture, and avoidance of herbicide use.
A Species of Conservation Concern: Listed as Endangered by the Missouri Department of Conservation and as Threatened by the U.S. Fish and Wildlife Service. It is declining due to loss of historic river floodplains and wetland habitat, which is caused by the construction of levees and locks and dams along the Illinois and Mississippi rivers, which have prevented flooding in many areas.
Americans have tried hard to channelize, manage, and tame the flows of our large rivers. As we do so, we arrest the natural rhythm of flooding that created the rich floodplain soil that is so good for farming—and the species that need occasional flooding decline and disappear.
This species needs periodic flooding or disturbance to eliminate competing vegetation and to provide the high light and moist soil that its seeds require to germinate. It responded rather well to the Great Flood of 1993, when its entire global range was flooded for 8-10 weeks.