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Perennial fern of the Polypodiaceae family, the common polypody is widely spread in Europe, temperate Asia, and North America. It colonizes rocks, old walls, stumps, wooded banks, and undergrowth, indifferently on acidic or neutral substrates, often in well-drained and partially shaded situations.
It forms spreading clumps 20 to 40 cm high, from a superficial, fleshy, and scaly creeping rhizome, whose progressive extension allows it to cover large areas. The fronds are simply pinnate, bright green and shiny, with entire, oblong, and slightly falciform pinnules, arranged regularly on either side of the rachis. The sori are round, clearly visible on the underside of the pinnules, yellow-orange then brown at maturity, devoid of indusium.
Unlike many ferns, Polypodium vulgare is semi-persistent to persistent depending on conditions; it can go dormant if summer drought is prolonged, but retains its foliage in sufficiently humid conditions. New fronds generally appear in late summer or autumn.
The rhizome was formerly used in folk medicine as a mild purgative and expectorant, under the name of wood licorice, due to a slight sweet flavor.
In cultivation, it adapts to most well-drained soils, in shade or partial shade, and thrives in the most unexpected situations: rock gardens, walls, undergrowth, but also at the base of eaves where it spontaneously settles in the joints, taking advantage of the surplus runoff water.