Dryopteris fragrans

Fragrant Fern

Fragrant Fern
Jap Lake, BWCAW
Photo © 2001 by Earl J.S. Rook

Flora, fauna, earth, and sky...
The natural history of the northwoods

Name:

• Dryopteris, from the Greek, drus (drys), "oak", pteris (pteris), "fern", "fern of the oak wood"
• fragrans, from the Latin, "fragrant"
• Common name from the aroma of the fronds when handled.
• Other common names include Fragrant Wood Fern, Fragrant Shield Fern, Fragrant Cliff Fern, Dryoptère Fragrante, Dryoptère Odorante (Qué), Tuoksualvejuuri (Fin)

Taxonomy:

• Kingdom Plantae, the Plants
• Division Polypodiophyta, the True Ferns
  • Class Filicopsida
    • Order Polypodiales
      • Family Dryopteridaceae, the Wood Ferns
        • Genus Dryopteris, the Wood Ferns
• Taxonomic Serial Number: 17536
• Also known as Polypodium fragrans, Thelypteris fragrans
• A northern species not closely related to North American Dryopteris. The only known hybrid is with Dryopteris marginalis, producing Dryopteris × algonquinensis.

Description:

• An atypical "Wood Fern" of rock faces.
• Fronds monomorphic, leathery, evergreen, strongly tapered at the base, and ½"-2½"× 2½"-16"; old leaves persistent as conspicuous grey or brown clump at plant base.
  • Petiole (leaf stalk) ¾"-4½" long, to 1/3 length of leaf, scaly throughout; scales dense, brown to red-brown.
  • Blades green, linear-lanceolate, and twice-cut; upper surface smooth, underside densely scaly; aromatic when handled.
  • Pinnae (primary leaflets) more or less in plane of blade, linear-oblong, and densely crowded, often overlapping and inrolled; lowest pairs much reduced.
  • Pinnules (secondary leaflets) with toothed edges; lowest pair longer than adjacent pinnules.
• Rootstalk short, thick, and erect; covered with brown scales.
  • Roots grey or black, sparse.
• Sori large, midway between midvein and edge of leaf, with distinct indusium.
  • Indusium ovate, whitish, and often overlapping, becoming brown with ragged margins.

Identification:

• Identifiable by its rocky habitat, small size, and persistent leaf bases.
• Distinguished from other Dryopteris species by looking nothing at all like them, from Common Polypody (Polypodium virginiana) by having twice cut fronds, and from the Cliff Ferns (Woodsia species) by its very densely crowded leaflets, its frond tapered at the base, and its short leaf stalk.
• Field Marks
  • rocky habitat
  • twice-cut fronds strongly tapered at base
  • densely crowded leaflets
  • persistent old leaves at base of plant

Distribution:

• Alaska to Newfoundland and Greenland, south to British Columbia, Alberta, Saskatchewan, Manitoba, Minnesota, Wisconsin, Michigan, New York, Vermont, New Hampshire, and Maine.
• Also northern Europe (Estonia and Finland) and Asia (Siberia and Japan).

Habitat:

• Shaded cliffs, talus, and scree; in crevices and on rock.
• Dry, moderately well drained rock, gravel, and till, with low organic content.

Fire:

Associates:

• Shrubs: Juneberry (Amelanchier spp.), Low Bush Honeysuckle (Diervilla lonicera)
• Herbs: Columbine (Aquilegia canadensis), Harebell (Campanula rotundifolia), Pale Corydalis (Corydalis sempervirens), Fringed Bindweed (Polygonum cilinode)
• Ferns: Common Polypody (Polypodium virginianum), Rusty woodsia (Woodsia ilvensis)
• Ground Covers: Rock Spikemoss (Selaginella rupestris)

History:

Uses:

Reproduction:

• By spore and vegetatively by rhizome.

Propagation:

• By rhizome division.

Cultivation:

• Hardy to USDA Zone 2 (average minimum annual temperature -50ºF)
• Cultural Requirements
• Sun to part shade
• Well-drained, rocky soil, with low organic content
• Dry to medium moisture
• A small fern suitable for alpine rock gardens.
• Occasionally available by mail order from specialty suppliers.

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