| Polystichum acrostichoides|
Its common name, Christmas fern, derives from its evergreen nature, with fronds growing to 30-80 cm long and 5-12 cm broad, pinnate with 20-35 pair of pinnules. The spores are produced on small pinnules toward the apex of the frond. It greatly resembles the Pacific Coast sword fern, Polystichum munitum, but does not make the huge clumps of that fern, and differs from it in the constriction of the fertile pinnules. Like other ferns of the genus Polystichum, it is allied to the wood ferns, genus Dryopteris, which it often is found growing close to.
It is one of the most common ferns in eastern North America, being found in a wide variety of habitats and locations. The Christmas fern is popular in cultivation because it is easy to grow and can be used in almost any setting or soil.
It has been noted that this fern can serve a soil conservation function on steep slopes. The fronds are semi-erect until the first hard frost, after which they recline to be flat on the ground, effectively holding in place fallen leaves so that they become soil on the slope.