Ekrt, L., Jessen, S., Novák, P., Vejvodová, K., Kalníková, V., Lustyk, P. and Fraser-Jenkins, C.R. 2025. Polystichum caucasicum sp. nov. (Dryopteridaceae), a new, surprisingly hexaploid fern species from the Caucasus. Phytotaxa. 736, 3 (Dec. 2025), 275–287. DOI:https://doi.org/10.11646/phytotaxa.736.3.4.