[3] Like other species in the Polytrichaceae, Polytrichum strictum has leaves with a single costa, vertical lamellae, a water-repelling cuticle, and rhizoids that appear to facilitate external water movement in addition to anchoring the plant.

[3] The reddish awn (formed by the slightly excurrent costa) and smooth, inrolled leaf margins separate P. strictum from other Polytrichum species; only juniper haircap moss (P. juniperinum) shares these attributes.

[1][3] It is characteristic of boggy peatland habitats dominated by Sphagnum mosses, but can also be found in wet heaths, tundra, sedge meadows, and peaty forests from low to high elevations; in warmer climates, it is largely confined to relict bogs.

[4] The lucky few sperm to land near the archegonia of a female plant (also borne terminally) use their two whiplash flagella to swim down the neck and into the venter, where one will fertilize the ovum.

[6] It is instrumental in preventing frost heaving in harvested peatlands, and research suggests it can be used in the restoration of unstable peat areas, although little is known about whether it aids or hinders Sphagnum growth.