Rhizome creeping to suberect. Fronds up to 90cm long, glabrous, dark green; pinnae tapering to a sharp point, bases of pinnae adnate (join directly onto) the rachis; young fronds brown to red; sori are as long as the pinnae; indusium linear, entire  (indusium = epidermal outgrowth which covers the sori when young).

Latin: attenuatum = tapering to a point; an apt description of the pinnae of this species which taper to a sharp point.

Greek: blechnon = fern.