A genus of about 260 species of ferns with a cosmopolitan distribution. The highest diversity is in eastern Asia, with about 120 species in China alone; the region from Mexico to Brazil has nearly 100 additional species; Africa (17 species), North America (15 species), and Europe (5 species) have much lower diversity. Polystichum species are terrestrial or rock-dwelling ferns of warm-temperate and montane-tropical regions (a few species grow in alpine regions).
Many ferns of this genus have stout, slowly-creeping rootstocks that form a crown, with a vase-like ring of evergreen fronds 30-200 cm long. The sori are round, with a circular indusium. The stipes have prominent scales. The genus differs from Dryopteris in the indusium being circular, not reniform, and in having stronger, more persistent fronds with a harder, somewhat rough, texture.
Hybridisation is frequent in the genus, with several named hybrids.
