Rhizome usually short, erect to oblique, sometimes creeping, sometimes forming short trunk, covered with shiny, narrow scales and often remnant bases of old stipes. Stipes green, blackish or reddish. Lamina usually once pinnate, sometimes undivided or lobed; in many species, pinnae of fertile fronds much narrower than in sterile ones; pinnae margins entire or finely toothed; lateral veins in sterile fronds single or forked, parallel, close together, free; in fertile fronds the soral veins run parallel and close to midrib. Sori forming a continuous band on either side of midrib or discrete, or sometimes confluent across midrib, in 1–3 rows; indusium ellipitc to linear, membranous, opening towards midrib; spores bilateral.
About 200–250 species, cosmopolitan; 25 occurring in Australia, 12 in Victoria.
Doodia was formerly treated as a separate genus but analysis of molecular data has shown it to be nested within those species traditionally regarded as comprising Blechnum
Reference, Christenhusz, M.J.M, Zhang, X.C. & Schneider, H. (2011). A linear sequence of extant families and genera of lycophytes and ferns. Phytotaxa 19: 7–54.