O. lineare is a reasonably common and nondescript turfed moss that occurs on tree trunk bases and charred wood. When sterile it can be quite difficult to distinguish from some species of Ditrichum. The leaves are linear with a nerve that fails slightly below the apex. Capsules are oblong, 1-2 mm long, light brown or yellowish-brown, and borne on a slender reddish-brown stalk about 1cm long. When mature, the capsules appear pleated.