Blechnaceae
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 dissimilar
Sterile fronds pinnate, pinnatisect or, if pinnatifid into numerous segments, then the segments not noticeably constricted at the base