Platanthera leucophaea


Platanthera leucophaea, commonly known as the prairie white fringed orchid or eastern prairie fringed orchid, is a rare species of orchid native to North America. It is listed as a threatened species in the United States on September 28, 1989. The IUCN does not currently recognize it as being at risk.

Distribution

Platanthera leucophaea is found in moist to wet tallgrass prairie, sedge meadows, fens, and old fields. For optimum growth, little or no woody encroachment should be near the habitat. Historically, the eastern prairie fringed orchid primarily in the Great Lakes Region with isolated populations in Maine, Virginia, Iowa, and Missouri. A historic record exists for Choctaw County, Oklahoma. The plant has not been observed in Oklahoma in the past 150 years. The major factor in the decline of the eastern prairie fringed orchid has been a loss of habitat due to grazing, fire suppression, and agricultural conversion.

Description

Platanthera leucophaea arises from a fleshy tuber. The plant can grow up to three feet tall. The leaves are long and thin.
The inflorescence is large and showy and may have up to 40 white flowers. It is distinguished from Platanthera praeclara, the western prairie fringed orchid, by its smaller flowers, more oval petals, and a shorter nectar spur.
The eastern prairie fringed orchid is a long-lived perennial. Its tuberous rootstalk helps it survive grass fires. Fires and rain stimulate the plant to grow and flower. The plant emerges each year in May and flowering begins by late June. The flowers are pollinated at night by large sphinx moths. Certain night-flying insects that are attracted to the orchid's fragrance are able to obtain its nectar with their long probosces. Others cannot because of the flower's long, narrow, oddly positioned nectar spur.