Pterygoneurum is apparently most closely related to Crossidium, and, like that genus, has chlorophyllose filaments (occasionally) in addition to the adaxial costal lamellae, and the stem is densely clothed with pale, brown rhizoids. Pterygoneurum is common in arid regions of the West, forming a dense, low turf in exposed soil. The hyaline awns and short setae are distinctive in the field.