(Boynton and Beadle) Blake
Echinacea laevigata, the smooth purple coneflower, is an Endangered Species Act federally listed endangered species of plant found in the piedmont of the southeastern United States. Most populations are found on roadsides and other open areas with plenty of sunlight, often on calcium- and magnesium- rich soils.
Its current range is within the states of Virginia, North Carolina, South Carolina, and Georgia, and it was historically also found in Pennsylvania and Maryland. It has been rare as long as it has been known, but a number of human activities and associated processes have reduced its range further. Today there are about 100 occurrences, and many of these are in poor condition. The amount of appropriate habitat available for this plant has been greatly reduced and it continues to decline.
This is a rhizomatous perennial herb that resembles its close relative, the common echinacea (Echinacea purpurea). The two can be told apart by the leaves, which are cordate (heart-shaped) in the common species. E. laevigata grows up to about 1.5 meters in height with a mostly naked, smooth, leafless stem. Any leaves are roughly lance-shaped. On top of the stem is a flower head containing narrow pink or purplish ray florets up to 8 centimeters long. The florets droop away from the center of the head. The small, tubular disc florets in the center are dark purple in color. Blooming occurs in May through July. The plant is pollinated by a number of insects, including honeybee (Apis mellifera), bumblebees (Bombus spp.), the bees Psithyrus citrinus and Xylocopa virginica, a number of butterflies, and Lygaeus kalmii, a bug. The fruit is an achene about half a centimeter long which is likely dispersed by birds and small mammals that collect them for food. Some vegetative reproduction has been observed with more than one stem coming from a shared rhizome or aboveground rosette of leaves.
The natural habitat for this species of plant is sunny openings in forested habitat. Open areas of this kind were made by wildfire, fires set by Native Americans, and the grazing activity of animals. The plant's preferred soils are rich in calcium and magnesium, and include limestone and marble, gabbro, and diabase. Plants that share the habitat included eastern red cedar (Juniperus virginiana) and rattlesnake master (Eryngium yuccifolium). There are several species of oak that occur, but these are stunted such that sunlight reaches the understory. When human impacts began to reduce the amount of forest habitat remaining in the region, the plant survived in other open, sunny habitat types, such as cedar barrens, clearcuts, roadsides, cleared areas around utility equipment, and limestone bluffs. Two thirds of the populations known since the plant was first discovered are now gone.
Populations of the plant were lost when the habitat was destroyed, or when it was degraded as natural processes of disturbance were prevented. The plant requires open habitat where it can receive sunlight. When fire suppression is practiced, the habitat becomes overgrown, and the open areas close; this has led to the extirpation of a number of historical populations. Habitat was destroyed outright during development, agricultural operations, road construction, and installation of utilities such as gas lines.
Continuing threats to the species include further destruction and degradation of the land, collecting of the plant by flora enthusiasts, vandalism, herbicides, and exotic plant species. When the plant was listed as an endangered species in 1992, most of the populations were small, with many containing fewer than 100 plants each, and half were located on roadsides where they are vulnerable to destruction. There is a fear that this plant may be targeted for commercial harvest in the pharmaceutical echinacea trade, but there is little evidence of this threat so far.
- USFWS. Echinacea laevigata (smooth coneflower) determined to be endangered. Federal Register October 8, 1992.
- Echinacea laevigata. Center for Plant Conservation.
- Echinacea laevigata. The Nature Conservancy.
- USFWS. Smooth Coneflower Recovery Plan. April 1995.
- Gadd, L. E. (2006). Pollination biology of the federally endangered Echinacea laevigata, smooth coneflower, in small, isolated populations. Master's thesis, North Carolina State University. pg 13.
- Echinacea laevigata. North Carolina Natural History Program.