Polystichum

Shield ferns are members of the Polypody (Polypodiaceae) family. The Greek derivation of the scientific name is poly (many) and stichos (row) referring to the rows of sori on each pinna. The common name refers to the shield or umbrella appearance of the indusium.

The most commonly cultivated native species in North Carolina is the Christmas fern (Polystichum acrostichoides).

Fossil records in Asia extend to the late Eocene about 49 million years ago.

Today this genus has become so well adapted to a wide range of climatic and environmental conditions that it is found on six continents and on many islands.  These ferns often reside in disturbed habitats like road cuts, talus slopes or stream banks.  Polystichum ferns therefore are suitable for woodland, native, rock, and children’s gardens. They may be used as specimens, groundcovers, accents or cover for wildlife.

Quick ID Hints:

• Polystichum are sturdy ferns and grow as single crowns or in a cluster
• Rachi have short stipes with discontinuous grooving between rachis and costa
• Stipes have prominent scales with hair-like cilia, they lack true hairs
• Fronds are mostly evergreen, pinnate to finely divided, frequently with shiny foliage and bristly toothed edges
• Pinnae frequently have thumbs
• Sori are round with a dot in the center (retracting indusium) and arranged in rows (usually single, rarely double rows), midway between the midrib and the margin
  One of the distinguishing features between Polystichum and Dryopteris species of ferns is the reniform (kidney-shaped) sori in the later genus.