Osmunda cinnamomea

Cinnamon Fern

Photo © Marty Lucas, Becknell and Lucas Media, Ltd., used by permission

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

Name:

• Osmunda, from the Saxon god Osmunder the Waterman, who hid his family from danger in a clump of these ferns.
• cinnamonea, from the Latin "cinnamon"
• Common name from the wooly, cinnamon colored spores borne on the fertile frond.
• Other common names include Buckhorn, Osmonde Cannelle (Qué), yamadori-zenmai (Jpn)

Taxonomy:

• Kingdom Plantae, the Plants
  • Division Polypodiophyta, the True Ferns
    • Class Filicopsida
      • Order Polypodiales
        • Family Osmundaceae, the Flowering Ferns (an oxymoron, of course)
          • Genus Osmunda, the Flowering Ferns
• Taxonomic Serial Number: 17219
• Osmunda ferns form spores on a modified frond. For this species, a spore-bearing frond grows from the rhizome separate from sterile fronds.

Description:

• A tall, deciduous, perennial fern of moist woods, 2'-5' tall.
• Fronds annual, erect, dimorphic
• Sterile Fronds light green, ovate to lanceolate, up to 5' tall and 6"-12" wide, forming symmetric clump, turning yellow then bronze in fall. Pinnae (leaflets) broadly oblong with persistent tuft of hairs on upper surface at base; deeply lobed, almost to rachis but lacking true pinnules.
• Fertile Fronds bright green, turning to rich cinnamon brown; shorter and narrower than sterile leaves with much smaller, nonphotosynthetic pinnae, withering after sporulation.
• Stem round and slightly grooved; at first covered with cinnamon-colored hairs, later smooth and green.
• Rootstalk stout, woody, and creeping to suberect
  • Roots fibrous, matted
  • Fiddleheads large, showy with silver-white hairs which turn rusty as fronds unfurl.

Identification:

• Unmistakeable when fertile cinnamon fronds are present.
• Distinguished from Ostrich Fern () by small tufts of rusty woolly hairs at the base of each pinna where the pinna meets the frond.
• Field Marks
  • distinctive, cinnamon-colored fertile, spore-bearing frond
  • twice-cut sterile fronds
  • utter absence of sori on green leaves

Distribution:

• Ontario to Newfoundland, south to Texas, Oaxaca, Veracruz, the Gulf Coast, and Florida; Cuba, Jamaica and Puerto Rico.
• Also Chiapas and Tabasco, south to Ecuador, Paraguay, and Brazil. The Russian Far East, Korea, China, Japan,Taiwan, northern Burma, NE Thailand, and Vietnam.

Habitat:

• Bogs, peatlands, thickets, wet woods, swamps, ditches, and streambanks.
• On poorly drained, acid soils with high organic content.

Fire:

• Fronds are killed by fire but the fern resprouts from rhizome. Has good fire tolerance, often showing vigorous rhizome growth after fire.
• Spores germinate on mineral soil, so it probably colonizes after fire.
• Where fire is of intensity or duration that it completely consumes the organic substrate, the fern will not survive.

Associates:

• Sphagnum Mosses (Sphagnum sp.)

History:

Uses:

• Fiddleheads up to 8" are sometimes collected in the spring, steamed or boiled, and eaten.

Reproduction:

• Reproduces by spores and vegetatively by rhizomes
• Spores have very short viability after release and either fail to germinate or germinate poorly after just a few weeks.
• Both sterile and fertile fronds expand during a short period in early spring. Leaf expansion is complete within about a month. Fertile fronds begin to wither in early summer, after sporulation is completed. Sterile pinnae begin to wither at the end of summer, and the leaf stalk somewhat later, until the entire above ground plant is dry.

Propagation:

• By rhizome division in fall or spring; however this species tends to take a long time to recover after division.
• By spores sown as soon as they ripen in mid to late summer.

Cultivation:

• Widely cultivated as an ornamental. Hardy to USDA Zone 3 (average minimum annual temperature -40ºF)
• Cultural Requirements
• Full sun if constantly wet; otherwise part shade in moist soil
• Organic, acidic soil (pH 4.5-7.0)
• Leave dead fronds over winter to protect crown.
• 3'-5' High x 2'-3' Wide
• Good for naturalizing in wet woodlands and as background for smaller, more colorful flowering plants.
• Available by mail order from specialty suppliers or at local nurseries.

Links:

• Fire Effects Information System (FEIS)

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