This is one of the green-flowered Platantheras, which I find incredibly hard to distinguish, both because many of the species are similar, but also because they interbreed and are, therefore found in many intermediate forms.
Platanthera aquilonis is one of the easier species to distinguish both because its lip is yellowish in color and because of its club-shaped spur. It is also one of the larger-flowered and more attractive species.
The individual flowers are less than 1 cm, but the plant, usually around 45 cm, bears many flowers, up to 60 per spike, and puts on a fair show as a result.
All the Platantheras have been and by some still are classified as Habenarias, and this species was once known not only as a Habenaria, but as H. hyperborea, now considered to be confined to Greenland.
We have not found this species as often as we have the other Platantheras, but when we've found it, it has been locally abundant, and always growing, as is the case with many in the genus, in marshy areas.
The plant ranges all across Canada and Alaska and across the northern United States as well and down into California and New Mexico.
I believe that this Platanthera aquilonis also, though the shape of the lip is quite different. The hooded flowers, the club-like spur and color of the lip seem to be diagnostic, but perhaps someone who knows these plants better than I do can correct me.