About Polystichum imbricans (D.C.Eaton) D.H.Wagner
This fern grows several erect, linear or lance-shaped fronds (leaves) that can reach up to 80 centimeters in length. Each frond is composed of many narrow, overlapping leaflets (pinnae), which measure 2 to 4 centimeters long and sometimes twist, with toothed edges. Round sori are arranged in two rows on either side of the midrib of each pinna, and each sorus is covered by a centrally attached, umbrella-shaped indusium. It differs from the related species Polystichum munitum mainly by having narrower fronds, because its leaflets are less elongated, and leaflets usually have an apiculate (pointed) tip. This fern easily forms hybrids; some of these hybrids are fertile and have been classified as separate species, for example Polystichum californicum, which is its hybrid with Polystichum dudleyi.
