Small Whorled Pogonia (Isotria medeoloides)
Family: Orchid (Orchidaceae)
Federal Status: Endangered, listed September 9, 1982
Best Search Time: Mid-May through Early-July
Description: Small-whorled pogonia has a greenish-white stem that grows between 3 – 13 inches (7.6 - 33 centimeters) tall. It gets its common name from the five or six grayish-green leaves that are displayed in a single whorl around the stem. When the leaves are well developed, a single flower or sometimes a flower pair rises from the center of the circle of leaves. The flowers are yellowish-green with a greenish-white lip. Each flower has three sepals of equal length that spread outward. The flowers are scentless, lack nectar, and are primarily self-pollinating. It produces fruit which ripens in the fall. The seeds contain very little food reserves and therefore need to fall on soil containing mycorrhizal fungi in order for the seed to germinate and seedlings to become established. An over-wintering vegetative bud may form in late August or September. Occasionally small whorled pogonia will reproduce vegetatively, without the use of seeds.
Habitat: Small whorled pogonia can be limited by shade. The species seems to require small light gaps, or canopy breaks, and generally grows in areas with sparse to moderate ground cover. Too many other plants in an area can be harmful to this plant. This orchid typically grows under canopies that are relatively open or near features that create long-persisting breaks in the forest canopy such as a road or a stream. It grows in mixed-deciduous or mixed-deciduous/coniferous forests that are generally in second- or third-growth successional stages. The soils in which it lives are usually acidic, moist, and have very few nutrients.
Distribution: Small-whorled pogonia is found sporadically across the eastern United States and Canada. In North Carolina, this species is extant in Burke, Cherokee, Guilford, Jackson, McDowell, Rutherford and Transylvania counties. It is considered historic in Haywood, Henderson, Macon, and Surry counties.
Threats: Habitat destruction is the primary threat to small whorled pogonia. Commercial and residential development have encroached upon populations and eliminated what once was productive habitat. Development has also decreased the amount of available habitat for deer, concentrating their numbers, which increases deer herbivory on these plants. Small-whorled pogonia also appears to suffer from low rates of seedling establishment, meaning new plants do not replace older ones as they die.
References:Buchanan, M.F. and J.T. Finnegan. 2010. Natural Heritage Program List of the Rare Plant Species of North Carolina. NC Natural Heritage Program, Raleigh, NC.
U.S. Fish and Wildlife Service. 1992. Small Whorled Pogonia (Isotria medeoloides) Recovery Plan, First Revision. Newton Corner, Massachusetts. 75 pp.
For More Information on Small Whorled Pogonia...
- U.S. Fish and Wildlife Service Environmental Conservation Online System
- Small Whorled Pogonia Recovery Plan
- U.S. Department of Agriculture Natural Resource Conservation Service Plants Database
- Center for Plant Conservation species profile
Dale Suiter, Fish and Wildlife Biologist, 919-856-4520 ext. 18
Species profile revised on August 29, 2011.