Terrestrial ferns with short-creeping or ascending, dictyostelic, rhizome. Plant entirely without scales or larger hairs, bearing only minute, few-celled, cylindrical glandular hairs on the whole plant.
The single genus Monachosorum is often placed in a separate family because it does not fit in any other family. Probably it is associated with Denstaedtiaceae (Copeland 1947; Tryon & Tryon 1982, as tribe). Christensen (1938) suggested affinity with Thelipteridacaeae but with very week evidence. Posthumus (in Backer & Posthumus 1939) placed M. subdigitatum in Anogramma of the Pteridaceae, which seems very unlikely. Smith et al. (2006) placed Monachosorum in Demmstaedtiaceae.
All chromosome counts seem to be based on N = 56. Monachosorum maximowiczii, with 2n = 112 is diploid, M. subdigitatum with 2n = 224 is tetraploid, and M. flagellare (Makino) Hayata with 2n = 336 is hexaploid. Possibly M. arakii Tagawa, also hexaploid, is a separate species with different parent species and/or combinations. The separately described Chinese species, recently generally referred to M. subdigitatum, often resemble M. arakii, and could well be hexaploid, too. As long as there are no chromosome counts available their position remains obscure. This is especially so, because different forms seems to merge into each other. This might be explained by the fact that meiosis in the hexaploid species is irregular, as mentioned by Iwatsuki (1995), and different kind of offspring and hybridising is possible for those hexaploids.