Orthilia secunda is a small herb in the wintergreen family (Pyrolaceae) with pale green flowers all produced on one side of the stalk (an arrangement known as a 'secund' inflorescence). Orthilia secunda most frequently occurs in forest and shrublands, but can also occasionally be found scattered in alpine tundra. Plants grow 5-15 cm tall, and have basal leaves and a flowering stem, and. Sometimes leaves also grow on the lower stem. Leaves are green and shiny, simple, short-petioled, ovate, and have a sharp-pointed tip, with the margins finely serrated. The stems have a few scales and 5-25 flowers held in a raceme on one side of the stem, slightly curved. Flowers are small, with five whitish green petals which are translucent at the tips, each 4.5-6 mm long. The five petals, though not fused, overlap to form a nodding bell. The single style is long, protruding from the flower, the stigma five-lobed. The flowers have 10 anthers, which—like other Pyrolaceae species—are inverted at maturity and release pollen by two pores. Fruits are capsules, slightly flattened globes, containing close to 1000 minute seeds. Though O. secunda can look similar to species in the closely related genus Pyrola, the single-sided raceme is a key trait to help recognize this species.
Orthilia secunda is a perennial plant with evergreen leaves. Plants typically flower in mid-summer.
Orthilia secunda is monoecious. The flowers of one-sided wintergreen are nectar-producing. It is visited by nectar and pollen-feeding species, primarily bees (Knudsen and Olesen 1993). A small experiment in Minnesota by Jensen (1961) found O. secunda was self-incompatible. The anthers open by two round pores at the end of tubes to release their pollen. Fruits are round capsules, splitting open at maturity to release circa 1000 minute seeds, spread by gravity, wind and water. Plants can also grow clonally from rhizomes (Beatty et al. 2008).
Orthilia secunda is a widely distributed circumpolar species with a boreal-montane distribution. One-sided wintergreen occurs in every province or territory of Canada, the western states, the Great Lakes and New England to northern Virginia. In Alaska, this species occurs throughout Southeast and Southcentral to the interior, the Brooks Range and the North Slope. There are a few localities reported from southwest Alaska, not reaching the Aleutian Islands. In Denali, this species is broadly distributed across the Park, on both sides of the Alaska Range.
Orthilia secunda has a wide elevational tolerance, occurring from 99 to 1247 m, but most commonly found on elevations of 300-500 m. On slopes above five degrees, there are more specimens from southern aspects than northern. It is found on all levels of inclination, and has a slight preference for slopes of 4-12 degrees.