Thanks, Pola!
I may easily agree that
'Bevis' is a good looking cultivar, no matter if representing a pure species or a hybrid in fact.
Unfortunately i don't know J.W. Dyce's publication of 'Polystichum Cultivars' or other articles done by him. Dyce got surely a huge knowledge in concern of ferns and other plants, although i do not EXPECT that he will have proved specific characters of
'Bevis' in detail so he could certainly exclude chances it represented a hybrid.
As i know the appearance and variability of
Polystichum aculeatum,
P. setiferum and their hybrid the best, i could not at all exclude that
'Bevis' represented a cultivar of
P. × bicknelli. Leaves of this cultivar do look somewhat more rigid, stiffer than with
P. setiferum, the upper side of the blade clearly more glossy, possibly darker green, and the pinnulae are less clearly stiped but rather adnate, by that tending towards
P. aculeatum. Last but not least
'Bevis' is said to bear nearby only aborted, sterile spores as usual with hybrids.
It was interesting to prove smaller details which are invisible upon photos to clear this
at last. Maybe a Polish botanist was interested to do this?
Erwin