Platanthera dilatata, also known as the white bog orchid or bog candle, is one of the widest-ranging orchids in the western hemisphere, with populations found from the West Coast into the Rocky Mountains, in every Canadian province and Alaska, along the Great Lakes, and in the Northeastern U.S.  Its flowers are bright white and t-shaped, with a relatively large hood (the upper sepal) and simple lateral sepals and lower lip.  Spur length and shape differs between three variations (var. dilatata, var. albiflora, and var. leucostachys) in what is thought to be the result of the plants adapting to different pollinators that are found across the continent.

Plant size varies dramatically depending on habitat – stunted alpine specimens may only reach a few inches tall while those of open wetlands are known to grow to a height of 3 to 4 feet.  Its leaves, found mostly on the lower quarter of the stem, are long and relatively narrow.

Despite its prodigious North American range, P. dilatata was only found in a handful of spots in Northwestern Pennsylvania, most recently in Crawford County in the early 1990’s.  Unfortunately, habitat loss, deer browsing, and pressure from invasive species have likely pushed those populations past their breaking point and P. dilatata is now listed as endangered (and presumed extirpated) in our state.

Sources:

Platanthera dilatata. North American Orchid Conservation Center.  Copyright 2011-2022.  See  Platanthera dilitata.