In the PPG I system, based on Gasper et al. (2016),[2] Blechnum is one of 18 genera in the subfamily Blechnoideae, and has about 30 species.

Plants in the genus Blechnum (as circumscribed in the PPG I classification) are mainly terrestrial or grow on rocks; few are epiphytes.

Their rhizomes may be upright or creeping and have scales with entire margins or at most a few very small teeth.

The leaf veins are usually free, dividing one to three times, each ending near the frond margin in an enlarged tip.

[2] Using the PPG I circumscription, as of December 2019[update], the Checklist of Ferns and Lycophytes of the World accepted the following species and hybrids.