Dryopteris expansa

Common Names

Spiny Wood Fern, Spreading Wood Fern, Northern Wood Fern, Arching Wood Fern, Shield Fern, Alpine Buckler Fern, Northern Buckler Fern, Northern Fern

Summary

Dryopteris expansa is a deciduous perennial fern in the Dryopteridaceae native to temperate regions of the Northern Hemisphere, including Greenland, much of North America, and parts of Europe and Asia. It forms upright tufts of finely dissected green fronds that are triangular to oblong-triangular, about 60–90 cm tall and 45–60 cm wide, arising from a scaly rhizome. Fronds are 3-pinnate-pinnatifid with the lowest pinnae longer, and sori are rounds on the undersides with reniform indusia. Common woodland habitats include cool, moist woods, forest margins, and damp moss on decaying logs; the plant tolerates shade to semi-shade and dies back tardily in winter; deer- and rabbit-resistance adds durability in mixed plantings. For cultivation, Dryopteris expansa prefers USDA zones 3–7, shade to semi-shade, and evenly moist, humus-rich soils that are well-drained; a range of soils from sandy to heavy clay with mildly acidic to neutral pH are tolerated, and this fern is non-invasive. Propagation occurs by spores or division in spring; maintenance is low, with occasional division to keep clumps from crowding. Uses include massing in woodland garden settings, borders, and containers, where its fine-textured, lacy fronds provide texture and form in shaded beds.

Lifecycle

Perennial

Height

1-3 feet

Spread

18-24 inches

Hardiness Zones

Zones 3-8

Sunlight Requirements

Ideally partial shade; tolerates partial sun to full shade.

Soil Type

Moist, humus-rich loamy soil with good drainage, mildly acidic to neutral pH.

Soil Drainage

Moist but well-drained

Soil pH

5.5-7, Acidic to neutral

Bloom Time

Does not bloom.

Foliage Color

Green

Fall Foliage Color

Green

Leaf Lifecycle

Deciduous

Growth Rate

Medium

Seasons of Interest

Spring, Summer, and Fall

Propagation Methods

Spores and Division

Attracts Wildlife

Attracts blue grouse and mountain goats as a food source