Common Fern

Foodplant / spot causer
Herpobasidium filicinum causes spots on frond of Gymnocarpium dryopteris

Foodplant / parasite
telium of Hyalopsora aspidiotus parasitises live Gymnocarpium dryopteris

Gymnocarpium dryopteris is a fertile allotetraploid species that arose following hybridization between G . appalachianum and G . disjunctum (see reticulogram). Its wide distribution over much of the north temperate zone has provided ample opportunity for secondary contact between G . dryopteris and each of its diploid parents, thereby resulting in a wide-ranging composite of abortive-spored triploid crosses ( G . disjunctum × G . dryopteris and G . appalachianum × G . dryopteris ). These relationships are shown on the diagram. Sterile triploid plants are not restricted only to areas where the range of the tetraploid overlaps with that of either diploid. Their broad distribution could be explained in part by their spores, which are of two types: malformed, black, and with very exaggerated perispores, or round with extensive netted perispores (K. M. Pryer and D. M. Britton 1983). The latter spore type is capable of germination and presumably permits the plants to reproduce apogamously. The name G . × brittonianum (Sarvela) Pryer & Haufler has been applied to the G . disjunctum × G . dryopteris hybrid formula (K. M. Pryer and C. H. Haufler 1993). The type of G . × brittonianum has aborted and round spores, and leaves that strongly resemble those of G . disjunctum . They are large, 3-pinnate-pinnatifid, and the second and third pairs of pinnae are sessile with basal basiscopic pinnules markedly longer than the basal acroscopic pinnules. Sterile triploid plants with a morphology similar to the type of G . × brittonianum are frequent. The biology of both of these cryptic hybrid taxa needs further study, which should lead to detailed morphologic descriptions and distribution maps.

Gymnocarpium dryopteris also hybridizes with both G . jessoense subsp. parvulum and G . robertianum .

Stems 0.5--1.5 mm diam.; scales 1--4 mm. Fertile leaves usually 12--42 cm. Petiole 9--28 cm, with sparse glandular hairs distally; scales 2--6 mm. Blade broadly deltate, 2-pinnate-pinnatifid, 3--14 cm, lax and delicate, abaxial surface and rachis glabrous or with sparse glandular hairs, adaxial surface glabrous. Pinna apex entire, rounded. Proximal pinnae 2--12 cm, ± perpendicular to rachis, with basiscopic pinnules ± perpendicular to costa; basal basiscopic pinnule usually sessile, pinnatifid or rarely pinnate-pinnatifid, if sessile then with basal basiscopic pinnulet often equaling or longer than adjacent pinnulet; 2d basal basiscopic pinnule sessile, with basal basiscopic pinnulet equaling or longer than adjacent pinnulet; basal acroscopic pinnule sessile, with basal basiscopic pinnulet longer than or equaling adjacent pinnulet. Pinnae of 2d pair usually sessile with basal basiscopic pinnule longer than or equaling adjacent pinnule and about equal to basal acroscopic pinnule; basal acroscopic pinnule equaling or slightly shorter than adjacent pinnule, often with entire, rounded apex. Pinnae of 3d pair sessile with basal basiscopic pinnule equaling adjacent pinnule and equaling basal acroscopic pinnules; basal acroscopic pinnule equaling or slightly shorter than adjacent pinnule. Ultimate segments of proximal pinnae oblong, entire to crenate, apex entire, rounded. Spores 34--39 µm. 2 n = 160.

Greenland; St. Pierre and Miquelon; Alta., B.C., Man., N.B., Nfld., N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon; Alaska, Ariz., Colo., Conn., Idaho, Iowa, Maine, Mass., Mich., Minn., Mont., N.H., N.J., N.Mex., N.Y., Ohio, Oreg., Pa., R.I., S.Dak., Vt., Wash., W.Va., Wis., Wyo.; n,c Europe; n Asia to China, Japan.

Cool, coniferous and mixed woods and at base of shale talus slopes; 0--3000m.

Polypodium dryopteris Linnaeus, Sp. Pl. 2: 1093. 1753; Dryopteris linnaeana C. Christensen; Lastrea dryopteris (Linnaeus) Bory; Phegopteris dryopteris (Linnaeus) Fée; Thelypteris dryopteris (Linnaeus) Slosson

More info for the term: climax

In white spruce climax forests of Alaska, light surface fires usually do not affect understory species composition, of which western oakfern is a part [22].  However, stand-replacement fires that completely eliminate white spruce result in early seral communities where western oakfern is not present. In cedar-hemlock forests of northern Idaho, western oakfern successively decreased in abundance on sites that were logged, slashpile-burned, broadcast burned once, and burned two or more times over a 30-year period [25].

More info for the terms: climax, prescribed fire, succession

In the East Slope Region of central Alberta, western oakfern is not present until the climax stages of succession following fire [9].  On severely burned sites in northern Idaho (where all trees and groundlayer vegetation was consumed), western oakfern appeared in the third postfire year only [32].  This occurrence was rare because western oakfern is not considered a fire-surviving species.  In the subboreal spruce zone of British Columbia, western oakfern was present within 10 years following fire on four sites ranging from fairly dry to wet [14].  Fires were broadcast burns following logging, and its effects on specific plants were not studied at the time of the fire. Hamilton's Research Papers (Hamilton 2006a, Hamilton 2006b) and Research Project Summary provide information on prescribed fire and postfire response of many plant species, including western oakfern, that was not available when this species review was originally written.

western oakfern
oak fern

More info for the term: rhizome

The deciduous western oakfern is delicate in appearance and grows up to 11.8 inches (30 cm) tall [17].  Its petioles are 4 to 12 inches (10-30 cm) long and parallel to the ground [21].  The blade is divided into three triangular leaflets [17].  Each petiole arises from a single node on the creeping rhizome [21].  Spore covers are absent [16].

Western oakfern has a circumboreal distribution [16].  In North America it occurs form Alaska south to isolated populations in Oregon and east across all provinces of Canada to the Atlantic Coast.  It occurs throughout New England south to Virginia and west to Ohio.  Scattered populations are found in the northern Midwest states of Wisconsin, Michigan, and Minnesota, and it reaches as far south as Iowa.  Western oakfern also occurs in isolated populations of the Intermountain West and in New Mexico and Arizona [28].  Gymnocarpium dryopteris ssp. disjunctum is found along the West Coast and in parts of Idaho and eastern Washington [18].

More info for the terms: fire regime, seed

Western oakfern has rhizomes which may allow it to sprout following fire [25]. Because spores are stored in the soil seed bank, fires that do not damage upper soil layers may not permanently eliminate western oakfern from an area. FIRE REGIMES: Find fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".

More info on this topic.

More info for the terms: chamaephyte, geophyte

   Chamaephyte    Geophyte

More info for the terms: hardwood, mesic

Western oakfern occurs on mesic to wet sites in mixed conifer and northern hardwood stands [20].  Soils are moist to well-drained, with pH ranging from 4.5 to 6.4 [7,10,36].  Soil textures are gravelly or sandy to silty clay loams [4,7].  Western oakfern grows at elevations from 21 to 1,700 feet (7-518 m) in the Adirondacks [20].  In Alberta it occurs from 1,960 to 4,300 feet (600-1,300 m), and in Idaho western oakfern occurs at elevations between 2,500 and 4,500 feet (760-1,370 m) [7,10].  Western oakfern occurs on moderately steep slopes and northeast to north and west aspects [7,10]. Some plant species associated with western oakfern include Alaska-cedar (Chamaecyparis nootkatensis), devil's club (Oplopanax horridus), alder (Alnus spp.), mountain maple (Acer spicatum), red-osier dogwood (Cornus sericea), twinberry honeysuckle (Lonicera involucrata), thimbleberry (Rubus parviflorus), prickly rose (Rosa acicularis), highbush cranberry (Viburnum edule), twinflower (Linnaea borealis), heartleaf arnica (Arnica cordifolia), starry Solomon's-seal (Smilacina stellata), and bluejoint reedgrass (Calamagrostis canadensis) [7,10,12,14,17,30].

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This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

     5  Balsam fir
    12  Black spruce
    13  Black spruce - tamarack
    16  Aspen
    18  Paper birch
    23  Eastern hemlock
    25  Sugar maple - beech - yellow birch
    26  Sugar maple - basswood
    27  Sugar maple
    35  Paper birch - red spruce - balsam fir
    37  Northern white-cedar
    38  Tamarack
    60  Beech - sugar maple
   107  White spruce
   201  White spruce
   202  White spruce - paper birch
   203  Balsam poplar
   204  Black spruce
   205  Mountain hemlock
   206  Engelmann spruce - subalpine fir
   212  Western larch
   213  Grand fir
   215  Western white pine
   217  Aspen
   218  Lodgepole pine
   221  Red alder
   223  Sitka spruce
   224  Western hemlock
   225  Western hemlock - Sitka spruce
   226  Coastal true fir - hemlock
   227  Western redcedar - western hemlock
   228  Western redcedar
   229  Pacific Douglas-fir
   230  Douglas-fir - western hemlock
   251  White spruce - aspen
   252  Paper birch
   253  Black spruce - white spruce
   254  Black spruce -  paper birch

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This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

   FRES11  Spruce - fir
   FRES18  Maple - beech - birch
   FRES19  Aspen - birch
   FRES20  Douglas-fir
   FRES22  Western white pine
   FRES23  Fir - spruce
   FRES24  Hemlock - Sitka spruce
   FRES25  Larch
   FRES26  Lodgepole pine
   FRES28  Western hardwoods

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This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

More info for the term: forest

   K001  Spruce - cedar - hemlock forest
   K002  Cedar - hemlock - Douglas-fir forest
   K003  Silver fir - Douglas-fir forest
   K004  Fir - hemlock forest
   K005  Mixed conifer forest
   K008  Lodgepole pine - subalpine forest
   K012  Douglas-fir forest
   K013  Cedar - hemlock - pine forest
   K014  Grand fir - Douglas-fir forest
   K015  Western spruce - fir forest
   K020  Spruce - fir - Douglas-fir forest
   K021  Southwestern spruce - fir forest
   K093  Great Lakes spruce - fir forest
   K096  Northeastern spruce - fir forest
   K099  Maple - basswood forest
   K102  Beech - maple forest
   K103  Mixed mesophytic forest
   K106  Northern hardwoods
   K107  Northern hardwoods - fir forest
   K108  Northern hardwoods - spruce forest

More info for the terms: frequency, top-kill

Fire can top-kill western oakfern, and repeated burning can significantly reduce it's frequency [25,32].

Grizzly bear in the Selkirk Mountains, Idaho, have been observed eating western oakfern fronds [1].  Elk on Vancouver Island eat western oakfern, but use is low in spring and summer [15].

More info for the term: forest

Publications listing western oakfern as a dominant species are as follows:

Preliminary classification of forest vegetation of the Kenai Peninsula,
   Alaska [30]
Forest habitat types of northern Idaho:  a second approximation [7]
Classification and management of riparian and wetland sites in northwest
   Montana [4]

More info for the terms: fern, fern ally

Fern or Fern Ally

More info for the term: tree

Western oakfern can interfere with the growth of Engelmann spruce (Picea
engelmannii) seedlings [5].  Glyphosate can injure western oakfern when applied
from July to September [26].  It controls growth of western oakfern following
harvesting, allowing growth of desired tree species.  Western oakfern responses
to logging vary.  In areas where logging leads to decreases in site
moisture, western oakfern will decrease [8].  In wet, high-elevation areas
logging can increase western oakfern abundance [25].

     AK  AZ  CO  CT  ID  IA  ME  MD  MA  MI
     MN  MT  NH  NJ  NM  NY  OH  OR  PA  RI
     SD  VT  VA  WA  WV  WI  WY  AB  BC  MB
     NB  NF  NT  NS  ON  PE  PQ  SK  YT

Because of its ease and success at transplanting, western oakfern is a desirable garden plant [16].

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Western oakfern unfolds its fronds in early spring [6] and senesces in autumn [16].

More info for the terms: constancy, cover

Western oakfern appears to decrease in constancy and/or cover following logging and burning [14].

More info for the terms: herb, rhizome

   Rhizomatous herb, rhizome in soil

More info for the term: hardwood

Western oakfern reproduces by spores and sprouts from rhizomes. The spores are adapted for high wind dispersal [18].  There is much outcrossing in this species, and no intragametophytic fertilization [18].  Spores have been found in soil seedbanks where adult plants are absent [23].  Spores have sprouted in a greenhouse from soil samples taken from beneath canopy gaps in northern hardwood forests [24].

More info on this topic.

This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

    1  Northern Pacific Border
    2  Cascade Mountains
    5  Columbia Plateau
    8  Northern Rocky Mountains
   11  Southern Rocky Mountains
   12  Colorado Plateau

More info on this topic.

More info for the terms: climax, cover, forest, mesic

Facultative Seral Species Western oakfern is an indicator of cool, moist sites and mid- to late-seral forests [4,21,22,30]. Western oakfern will grow on disturbed sites before canopy cover is established in the subboreal spruce (Picea) zone of British Columbia [14].  It is present in that zone in both mesic seral communities and climax forests.  Similarly, in spruce-hemlock (Tsuga) forests of southeast Alaska western oakfern will begin establishing in 25- to 35-year-old stands following disturbance by logging or fire [1].  They will then dominate the understory for the following century.  Western oakfern has been used as a site-quality indicator species on lodgepole pine (Pinus contorta) and white spruce (Picea alba) stands in west-central Alberta [34].  It is also used as a secondary indicator of slope instability in grand fir (Abies grandis)/pachistima (Pachistima myrsinites) habitat types on the Clearwater National Forest, Idaho [27].

Dryopteris disjuncta (Ledeb.) Mort.
Dryopteris linnaeana Christens.
Phegopteris dryopteris (L.) Fee
Thelypteris dryopteris (L.) Slosson

The commonly accepted scientific name for western oakfern is Gymnocarpium
dryopteris (L.) Newm. in the family Polypodiaceae. There are two
subspecies as follows [18]:

Gymnocarpium dryopteris ssp. disjunctum (Rupr.) Sarvela
G. dryopteris ssp. dryopteris

The synonym Dryopteris disjuncta is used frequently in the literature
[8,9,22].

Gymnocarpium dryopteris, the western oakfern, common oak fern , oak fern, or northern oak fern, is a deciduous fern of the family Cystopteridaceae. It is widespread across much of North America and Eurasia. It has been found in Canada, the United States, Greenland, China, Japan, Korea, Russia, and most of Europe.