Blechnum L.

18 species in AUST. (11 endemic, 7 native); all states and territories

Terrestrial ferns. Rhizome usually erect or oblique, sometimes creeping or forming a short trunk up to 60 cm high, with a complex dictyostele, clothed with scales which are non-clathrate, usually thick, linear to ovate, black or dark brown or chestnut-coloured or with a dark centre and pale borders. Stipes not articulated to the rhizome, with several vascular strands. Fronds uniform or dimorphic; the fertile fronds usually much narrower than the sterile ones. Lamina simple, pinnatifid or pinnate in the Australian species, coriaceous or sometimes herbaceous, glabrous or clothed with a few scales; margin entire or serrate. Pinnae articulate to the rhachis in some species, often auriculate; the sterile flange beyond the sorus broad in some species but almost non-existent in others. Veins free in the sterile fronds, simple or once or twice forked, often prominent; a vascular commissure parallel to the costa in the fertile fronds. Coenosori linear, mostly continuous, rarely interrupted, superficial, one on each side of and parallel to the costa, close to the latter, often confluent with age and covering the whole of the lower surface of the fertile pinnae. Indusium linear, marginal or intramarginal, membranous, attached to the fertile commissure and opening towards the costa. Sporangia with an annulus including 14–28 thick-walled cells. Spores bilateral, reniform to almost globular, with or without a perispore.