The Trifid holly fern (Polystichum tripteron) belongs to the Polypodiaceae (the Polypody family). It is a summer-green fern that is native to throughout Japan, as well as the Korean Peninsula, eastern China and eastern Russia. This fern grows in wet forests on low mountains, and can reach 30-60 cm in height. The leaves are unipennate and lanceolate with 20-35 pairs of pinnae. It is difined by the cruciate, trifurcated basal pinnae.