Narrow, compressed, two-edged, cartilaginous, scarlet fronds, main axes dark brownish-red, to 300 mm long. Branching abundant, distichous, subdichotomous or alternate, terminal branchlets acute, fringed with short marginal proliferations. Tetrasporophyte is Haematocelis fissurata, a thick crust with oily fissures, with which it is sometimes found.