Wildlife on Walls: 10. Brittle Bladder Fern

Brittle bladder fern Cystopteris fragilis is one of the characteristic wall ferns of North East England, growing in crevices in shady limestone walls or in mortar and often thriving in old industrial sites, such as the inner walls of railway bridges and the ruins of old lead mine workings in the Durham dales.

It owes its common name to the shape of the coverings over the clusters of spores on the underside of its fronds and to the brittleness of the frond stems, which are succulent and snap easily.

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