D. foliosum occur in small patches up to 5 mm tall. The leaves are dull brownish-green, undulate and strap-like, 4.5-6 mm long, with an acute or blunt tip. The poorly defined nerve is a useful character for non-fertile plants. When fertile, the plant is unmistakable, with sessile capsules about the shape and size of a grain of wheat (about 4 mm long and 2 mm wide), topped by an oblique lid. The leaves surrounding the capsule may be up to 8 mm long, and have long-toothed margins.