Another nod of appreciation to Kathleen Garness for sending along a photograph from Illinois. Thank you!
“Here in Illinois, I have seen [Platanthera lacera] in wet prairie potholes and sandy moist swales, often with marsh shield fern, marsh phlox, and grass pink orchids, Calopogon tuberosus. It’s not yet listed as threatened or endangered in our state, but still is quite uncommon, especially due to the incursion of phragmites and reed canary grass in these habitats. Some people get it confused with Platanthera leucophaea in photos, but there is such a difference in size and flowers, once you have seen them both they are easily distinguished!”
I also note that Orchids of Wisconsin also explains the difference in their factsheet on Platanthera lacera.
Green fringed orchid is native to much of eastern North America. Additional photographs are available from Missouri Plants: Platanthera lacera, and the Nova Scotia Wild Flora Society: Platanthera lacera.