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Small Whorled Pogonia

Small Whorled Pogonia (Isotria medeoloides)

FAMILY: Orchidaceae

SYNONYMS: Arethusa medeoloides Pursh; Isotria affinis (Austin) Rydberg; Odonectis affinis (Austin) Schlechter; Pogonia affinis Austin ex A. Gray

HABIT: Herbaceous perennial, to 25 cm. 

Flowering: mid-May to mid-June; Fruiting: June to August.

SIMILAR SPECIES: Vegetative plants resemble the vegetative plants of the common Indian Cucumber-root, Medeola virginiana, a member of the Liliaceae. Flowering plants could only be confused with the Larger Whorled Pogonia, Isotria verticillata, which differs in having larger sepals and longer peduncles, in addition to other, more obscure, vegetative characters. Also I. verticillata is colonial while I. medeoloides is not colonial.

TOTAL RANGE: Irregularly at widely scattered stations from s. ME to NC, w. to s. Ontario, MI and MO.

STATE RANGE: Post-1990 record from Hocking County. Pre-1990 record from Scioto County.

HABITAT: Often the habitat for this species is an open, second-growth stand of hardwoods.

HAZARDS: Maturation of habitat through succession; removal of canopy by logging activities; destruction of habitat for development purposes.

RECOVERY POTENTIAL: Unknown, but probably poor. This species is quite rare throughout its range, and populations tend to consist of few individuals.

INVENTORY GUIDELINES: Plants should not be collected, and disturbance to populations should be kept to a minimum. It should be noted that a Federal permit is required to collect this species.

COMMENTS: Isotria medeoloides is considered the rarest species of North American orchid. Populations are usually few in number, and easily may go undetected. It’s rather generalized habitat makes this a difficult plant to seek out and successfully locate new populations, and its small size make it easy to overlook. While rather distinctive when in bloom, vegetative plants could easily be dismissed as the more common Isotria verticillata, or sterile plants of Medeola virginiana, the Indian cucumber-root. I. medeoloides also blooms approximately two weeks later than I. verticillata. The Scioto county record is from a single plant located in Shawnee State Forest in 1985. It is documented by photographs deposited at the University of Michigan herbarium.

SELECTED REFERENCES:

Case, Frederick W. Jr. 1987. Orchids of the Western Great Lakes Region. Cranbrook Institute of Science, Bull. 48. 251 p.

Gleason, H.A., and A. Cronquist. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. New York Botanical Garden, Bronx, New York. 910 pp.

Luer, Carlyle A. 1975. The Native Orchids of the United States and Canada excluding Florida. The New York Botanical Garden. 361 p.

Updated 7/2020

For more information contact:

Ohio Division of Natural Areas and Preserves

614-265-6453