Journal archives for December 2021

02 December, 2021

Likely wrong identifications of Polystichum × potteri in Vermont, USA and Nova Scotia, Canada

This post is written to clear some apparent wrong IDs of the fern hybrid Polystichum × potteri = Polystichum acrostichoides × braunii done and caused by me.
Please keep in mind that some, but not all my suggestions will be erroneous.

13 Observations which are currently, on 02.12.2021, identified as Polystichum × potteri

@choess @cgbb2004 @cchapman @seanblaney @charlie @connieyoungstrom @dbmcc09 @ebsessa @hayleykolding @hcray @jwatkins92 @msundue @pamdarrow @randyfredericks @michael_oldham @eralverson @david1945wagner @grazing @rroutledge

Since i am well familiar with several kinds of the genus Polystichum, in especial the ones native to Europe and northern North America, i added lots of IDs. In course of that i reviewed several kinds of hybrids as well, which in turn are quite hard to detect and to identify, in especial upon photos.

Why do i expect, that some IDs as the hybrid P. × potteri will likely be erroneous, and what was right instead?
Well, P. braunii, the one parental kind of the hybrid with (nearby) bi-pinnate fronds is ± uniform in my home region in Styria, Austria, as well as in major part of the native range.
The only, but slight exception was, that very large grown individuals do tend to have clearly bi-pinnate blades, and that the basal pinnae may grow somewhat longer than for usual.
However, there is a slight exception with the population of P. braunii native to eastern USA and Canada.
So far i noted this correctly, in that region are two types of individuals, the ones which look quite the same as others of distant populations, and the ones with minor, yet visible differences.

What is differing between "usually looking" and deviating types in eastern North America?
This is nothing but my personal perception by watching photos, however, i am best trained in recognizing visual patterns. [thus, no supporter of AI suggestions - well, another story]
I repeatedly recognized that some individuals of P. braunii had slightly darker green, glossier, and "rigid" looking fronds, combined with somewhat less divided pinnae, so that the pinnulae (pinnae of 2nd order) are adnate by a wider base than "for usual".
Although i do not know if these slightly differing characters were the same with Polystichum braunii var. purshii Fernald, i wouldn't support this distinction, at least right now.

Individuals as described above, which do look like influenced in appearance by their relative Polystichum acrostichoides do make the separation from true hybrids P. × potteri even harder and may or will have caused my wrong IDs.

What do i attend now?
I liked to critically review all obss. identified as Polystichum × potteri, and alert all engaged and interested iNat members.
I am sorry for having provoked erroneous IDs in case!

Best regards to all

the one who loves ferns - as well as other living creatures!

Posted on 02 December, 2021 11:19 by erwin_pteridophilos erwin_pteridophilos | 1 comment | Leave a comment