Parablechnum C.Presl, Abh. Königl. Böhm. Ges. Wiss.

Smith, Alan R. & Kessler, Michael, 2018, Prodromus of a fern flora for Bolivia. XXXIII. Blechnaceae, Phytotaxa 334 (2), pp. 99-117 : 110

Parablechnum C.Presl, Abh. Königl. Böhm. Ges. Wiss. , ser. 5, 6: 469. 1851.

Parablechnum is characterized by (usually) strongly dimorphic leaves (monomorphic in P. monomorphum ), with the fertile pinnae much narrower and without green laminar tissue; erect or suberect rhizomes (creeping in P. repens ); and ovate or ovate-lanceolate, bicolorous or concolorous scales one cell thick on the rhizome apices and petiole bases. Blades are truncate proximally, the lowest pinnae are the longest, or nearly so. Leaf venation is free and ± parallel, and sori are linear and usually extend nearly the entire pinna length. In some species, tuberculate or peg-like aerophores are produced at the pinna bases. There are about 65 species in the Neotropics, southern Africa, southeastern Asia, Australasia, and the southern Pacific islands. We here recognize 15 species for Bolivia, where they are found mainly in humid montane forests.

Parablechnum is by far the largest genus in the family, and certainly one of the most difficult, taxonomically. The distinctiveness of this group has long been recognized, and the species are in need of monographic study. Chromosome counts on at least 10 species, from both Australasia and the Neotropics, reveal a unique base number in the family, x = 28, although a few other numbers have been reported in some species (e.g., x = 31, 34). Nearest affinities within the family are unresolved.