Cambricum is a southern lime-lover and easiest by virtue of very restricted distribution in Herefordshire (the Lower Wye NCA), predilection for south-facing limestone, and having the most distinct form of the three. Distinguishing the other two is more difficult and in an effort to get my thoughts straight I have distilled information from CN Page into an A4 sheet (attached) which will sit on my phone. It would be nice to be able to say something nuanced about these in a county with widespread but very local and often weakly base-rich soils set in often weakly acid ones, and largely devoid of actual outcrops. We are well within the core range of both and their hybrid (Manton’s Polypody Polypodium x mantoniae) is likely. It could easily be the second most common fern hybrid in Herefordshire, in spite of a mere two records to date. But the first step in spotting the hybrid is fixing on the parent species, so here goes:
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