Autumn Fern or Japanese Red Shield Fern

(Polypodiaceae - Polypody Family)

Form

• small herbaceous semi-evergreen fern
• maturing at about 1.5' tall by 2' wide
• arching clump growth habit

Culture

• partial shade to full shade
• performs best in moist, rich, deep, well-drained, organically-supplemented soils in partial shade; not tolerant of urban stress conditions, including sunny sites, high intensity reflected light, heat, drought, poor soils, compacted soils, or pollution
• propagated primarily by crown division, but also by spores
• Polypody Family (the largest Family of ferns), with few disease or pest problems (crown rot can occur in poorly drained soils)
• moderately available in container form

Foliage

• delicate, fine-textured, and moderately shiny, unfolding from a fiddlehead (crosier) to a copper-red frond (autumnal in color, hence the common name) to form a gently arching glossy leaf that changes from copper to bronze to kelly green as it matures
• pinnately compound, to 2' long for each frond, with the foliage radiating and arching from the crown, sometimes with several flushes during the growing season, very slowly senescing and dying back in Winter, being semi-evergreen in Northern climates, but evergreen in Southern climates

Flowers

• technically not applicable; many ornamentally insignificant brown-red sori (the reproductive structures) occur in July on the undersides of the leaflets

Fruits

• technically not applicable (spores are shed from the sori as the season progresses)

Twigs

• not applicable

Trunk

• not applicable

ID Summary

• pinnately compound fronds emerge as bronzed fiddleheads, unfurling and expanding to yield a clump of foliage that matures to a dull shiny, medium-green group of fronds, radiating from the crown, often with more than one flush of growth during the season; sori appear on the undersides of the leaflets, shedding spores later in the season

USAGE

Function

• a low-growing accent foliage perennial for shady conditions found at north- or east-facing foundations, under large trees, in woodlands, or at the border; also effectively used in shady portions of Japanese Gardens

Texture

• medium-fine texture
• average density

Assets

• new foliage emerges from the center of the crown as a copper-red color, which is unique among ferns
• semi-evergreen foliage

Liabilities

• not urban tolerant, and generally requiring good topsoil, well-drained subsoil, adequate and continuous moisture, and shady conditions to thrive

Habitat

• zones 5 to 8
• native to Japan and China

SELECTIONS

Alternates

• other plants for full shade or dappled shade situations, including ferns (Athyrium, Matteucia, Osmunda, Polystichum, etc.), perennials (Astilbe, Brunnera macrophylla, Hosta, Pulmonaria, Stylophorum diphyllum, etc.), or groundcovers (Gaultheria procumbens, Hedera helix, Mitchella repens, Symphytum grandiflorum, Vinca minor, etc.)

Variants

• the species form is the only type commercially available

NOTES

Translation

• Dryopteris is translated from the Greek as "oak fern".
• erythrosora translates as "red sori", referring to the spore-bearing structures on the undersides of the leaflets.

Purpose

• Autumn Fern is one of the few ferns that has fronds that are not solid green in color (at least initially).

Summary

• Dryopteris erythrosora is known as an accent fern with emerging fronds that are copper-red in color, slowly changing to kelly green by mid-Summer, and being evergreen in Southern climates.