A transcontinental species of the Boreal and Mixed Forest Regions and adjacent regions of the Montane and Deciduous Forests and Tundra. Occurring in moist woods, swamps, bogs, along wooded streams and in wet meadows, responding well to "cold bottom" conditions. Is frequent in swamps dominated by Eastern White Cedar, accompanied by Black Spruce, White Spruce, Tamarack, Black Ash and Yellow Birch. Prefers moist habitats in the south, but is frequent in drier upland situations northward. Dense, dryish Eastern White Cedar thickets sometimes shelter this orchid. Here the substrates are usually sands and sandy loams.

Height to 20 cm; stem smooth, leafless, green or greenish-yellow with pale tubular sheaths at base.
Raceme a loose group of 3-20 flowers.
Flowers small, mostly pale greenish-yellow, sometimes tinged with red-brown; petals in contact with dorsal sepal to form a hood; lip arcuate-recurved, 3-lobed , lateral lobes like small triangular upturned teeth near the narrowed base; lip white, in the typical variety: column, upper and lower surfaces of lip with deep magenta or ruby spots.
In var. verna, the whole plant except the lip is lacking the red and brown colouration; the lip is white without spots; odour is faint and acrid, or richly floral, or lacking. Verna is the variant generally found in mesic forest habitats

Plant is widespread, abundant and easily located in a variety of wooded situations. Tends to form large clumps and extensive colonies. It is the only member of this genus with distinctively yellowish-green colouring in the stem and flowers. Later in the season, the orchid remains recognizable because it develops fat yellowish drooping seed pods.

Orchids of Ontario
The Canadian Field-Naturalist Vol III - 1
The Orchids of Bruce & Grey