Sori borne on elongated vascular commissures parallel to the midvein or attached to the outer walls of the areolae but facing the midvein Blechnaceae
Coenosori in a continuous or almost continuous line on each side of the midrib covering the vascular commissures, having a membranous indusium opening inwards towards the costa. Veins of the sterile fronds free Blechnum
Fertile and sterile fronds similar; the fertile pinnae or frond-segments slightly narrower to one-third of the width of the sterile