This monotypic genus was circumscribed by Seberg, Frederiksen, & C. Baden in Seberg et al. (1991). They explain that the name (peri, around and dictyon, net) refers to the netlike withering of the basal leaf sheaths. Its only species is Peridictyon sanctum (Janka) O. Seberg, S. Frederiksen, & C. Baden. Synonyms are Festuca sancta Janka, Brachypodium sancta (Janka) Janka, Agropyron sanctum (Janka) Hackel, Festucopsis sancta (Janka) Melderis. It occurs in eastern Greece and southern Bulgaria.
Festucopsis (C.E. Hubbard) Melderis
After removal of Peridictyon, Festucopsis becomes a genus of two species (Seberg et al. 1991). These, their synonyms and distribution, are summarized below. The information comes from Seberg et al. (1991).
Festucopsis serpentini (C.E. Hubbard) Melderis
Synonyms: Brachypodium serpentini C.E. Hubbard; B. albanicum, Acht. & Kitan in Kitan.; Agropyron kosanii Cernjav. & Soska in Cernjav.; A. festucifolium Cernjav & C. Chase in Cernjav.
Distribution: Albania
Festucopsis festucoides (Maire) A. Löve
Synonyms: Agropyron festucoides Maire; A. festucoides f. atherantha Brichambaut & Sauvage; A. pseudofestucoides Emb. A. pseudofestucoides var. muticum Emb.; A. pseudofestucoides f. muticum (Emb.) Brichambaut & Sauvage; A. festucoides var. pseudofestucoides subvar. muticum (Emb.) Maire & Weiller; . A. pseudofestucoides var. acutiflorum Emb.; A. pseudofestucoides f. acutiflorum (Emb.) Brichambaut & Sauvage; A. festucoides var. pseudofestucoides subvar. acutiflorum (Emb.) Maire & Weiller; A. festucoides var. acutiflorum f. leiorrachis Maire; A. festucoides var. leiorrachis (Maire) Maire & Weiller.
Distribution: Morocco (High Atlas)