This species is typically found growing on exposed and dry rock surfaces that protrude from the soil. Their habitats can range from sea level to alpine elevations. Their distribution is widespread in temperate regions of the Northern Hemisphere. They range includes the southern Appalachian Mountains to the states west of the Great Lakes, from California northward to Alaska, as well as eastward in the Rocky Mountains of Colorado.
Racomitrium heterostichum has many growth forms that can vary significantly, making it difficult to identify this species in the field. The gametophytes generally form mats that are fixed onto its substratum. The color of the plants can range from dark green to brownish-green. When a hair point is present and long, the plants can at times seem whitish-green in color. This species usually has a white hair point and the plant may be irregularly to regularly branched.
The shape of the leaves can range from ovate-lanceolate to lanceolate. The costa is typically strong and one or both sides of the leaf can sometimes be recurved. Generally, the leaf margins are toothed.
The stem, which can be 2-6 cm long, is often branched. Short tuft-like branches can be present or absent on the stems of this species.
The sporophytes are common and typically mature in the spring. The sporophyte is reddish-brown in color when young and becomes pale brown as it reaches maturity.
At maturity, the sporangium is usually brown and smooth. However, the presence of wrinkled on the capsule may be present when dry. Small papillae can be present on the apex of the calyptra.
The seta is normally twisted clockwise and can reach heights between 4-8 mm.
The spores of R. heterostichum are finely papillose.