North Dakota Field Office
Mountain-Prairie Region

Western Prairie Fringed Orchid
(Platanthera praeclara)

leaves

western prairie fringed orchid by US Fish & Wildlife Service
Photo by US Fish & Wildlife Service

Official Status:  Threatened.  Threatened species are animals and plants likely to become endangered species within the foreseeable future throughout all or a significant portion of their range.

Listed:   54 Federal Register 39863; September 28, 1989.

Historical Status:  The western prairie fringed orchid was historically found throughout the tallgrass regions of North America.  This included the Dakotas, Nebraska, Kansas, Oklahoma, Missouri, Iowa, Minnesota, and Manitoba.  The Mississippi River was the eastern limit of its range.

Present Status:  The western prairie fringed orchid has experienced at least a 60 percent decline from historic levels.  Presently, populations are known from 175 sites in six States and Canada.  The species appears to be extirpated from South Dakota and Oklahoma.  North Dakota has one of three large populations, the other two are in Minnesota and Manitoba, Canada.  In North Dakota, the population is found on and near the Sheyenne National Grasslands in the southeastern part of the State.  This population numbers over 7,000 individuals.

Habitat:  The western prairie fringed orchid occurs in moist tallgrass prairies and sedge meadows.  In North Dakota, it is commonly found with sedges, reedgrass, and rushes or where those plants meet big bluestem, little bluestem, and switchgrass.  The western prairie fringed orchid is well adapted to survive fires.  Light grazing does not appear to negatively affect the western prairie fringed orchid, although researchers are still studying the relationship.

Life History:   Vegetative shoots of the western prairie fringed orchid emerge in late May.  Flowers do not emerge until mid-June to late July.  The entire plant can display flowers for about 21 days, with individual flowers lasting up to 10 days.  Flowers must be pollinated for seed production. Pollination of the western prairie fringed orchid appears to be accomplished only by hawkmoths.  The microscopic seeds are dispersed by wind and flooding in early fall.  The western prairie fringed orchid is a perennial; however, differences exist between North Dakota and Minnesota populations in how long an individual plant lives.  In North Dakota, most plants live 3 years or less and show higher rates of mortality than Minnesota plants.

Aid to Identification:   The western prairie fringed orchid is distinguished by large, white flowers that come from a single stem.  Up to 20 flowers may occur on a single plant.  The flower is fringed on the margins, giving it a feathery appearance.  The western prairie fringed orchid grows up to 3 feet high.  The 2 to 5 leaves are narrow and hug the stem.

Reasons for Decline:   The main reason for the decline is that historic prairie habitat has been converted to cropland.  Herbicides and the introduced plant, leafy spurge, may also have a negative affect on the western prairie fringed orchid.  Heavy grazing and early haying can be detrimental.

Recommendations:   Notify the U.S. Fish and Wildlife Service of any suspected western prairie fringed orchids.  This includes populations that were visible in the past, but have not recently been observed.

Comments:  The eastern prairie fringed orchid is similar to the western prairie fringed orchid; however, it inhabits primarily areas east of the Mississippi River.  The eastern prairie fringed orchid is also listed as a threatened plant.

References:   Western prairie fringed orchid (Plantanthera praeclara) Recovery Plan. U.S. Fish and Wildlife Service, Ft. Snelling, Minnesota. September 1996. vi+ 101 pp.

western prairie fringed orchid by US Fish & Wildlife Service
Photo by US Fish & Wildlife Service

Last updated: February 19, 2013