- Pteridium, from the Greek pteris
- aquilinum, from the Latin, "eagle like"
- Bracken, an old English word for all large ferns, eventually applied to
this species in particular.
- Other common names include: Brake, Brake Fern, Eagle Fern, Female Fern,
Fiddlehead, Hog Brake, Pasture Brake, Western Brackenfern, Grande fougere,
Fougere d'aigle, Warabi (Qué), Örnbräken,
Bräken, Slokörnbräken, Taigaörnbräken, Vanlig Örnbräken
(Swe), Einstape (Nor), Ørnebregne (Dan), Sananjalka
(Fin), Adlerfarn (Ger), Kilpjalg, Kotkajalg, Põldsõnajalg,
Seatinarohi, Sõnajalg (Estonia)
- Kingdom Plantae, the Plants
- Division Polypodiophyta, the True Ferns
- Taxonomic Serial Number: 17224
- Also known as Pteris aquilina, Asplenium aquilinum, Allosorus aquilinus,
Ornithopteris aquilina, Filix aquilina, Filix-foemina aquilina, Pteris latiuscula
- Considered a single, worldwide species, although some disagree
- A large, deciduous, rhizomatous fern
- Fronds 1'-3' w/leaf stalk up to 3'' but usually shorter than leaf blade.
Blades of frond divided into pinnae, the bottom pair sometimes large enough
to suggest a three part leaf. Pinna divided into pinnules. On
fertile fronds the spores are borne in sori beneath the outer margins of
the pinnules. Fronds are killed by frost each winter and new fronds
grow in spring. Dead fronds form a mat of highly flammable litter that
insulates the below-ground rhizomes from frost when there is no snow cover.
This litter also delays the rise in soil temperature and emergence of frost-sensitive
fronds in the spring.
- Rhizomes are the main carbohydrate and water storage organs (87%
water). Rhizomes can be up to 1" diameter and branching is alternate. The
rhizome system has two components. The long shoots form the main axis or
stem of the plant. They elongate rapidly, have few lateral buds, do not
produce fronds, and store carbohydrates. Short shoots, or leaf-bearing lateral
branches, may be closer to the soil surface. They arise from the long shoots,
are slow growing, and produce annual fronds and many dormant frond buds.
Transition shoots start from both short and long shoots and may develop
- Roots thin, black, brittle extending from the rhizome to over 20"
inches into the soil.
- Brackenfern is a large, coarse, perennial fern that has almost horizontal
leaves and can grow 1½ to 6½ feet tall (sometimes up to 10
feet). Unlike our more typical broadleaf perennials, this primitive perennial
lacks true stems. Each leaf arises directly from a rhizome (horizontal underground
stem), and is supported on a rigid leaf stalk. In addition, brackenfern
does not produce flowers or seeds. Instead, it reproduces by spores and
creeping rhizomes. This species often forms large colonies.
- Root system - The black, scaly, creeping rhizomes (horizontal underground
stems) are ½ inch thick, and can grow as much as 20 feet long and
10 feet deep. Stout, black, wide-spreading roots grow sparsely along the
- Seedlings & Shoots - The curled leaves (fiddleheads) emerging from
rhizomes in the spring are covered with silvery gray hair.
- Stems - The leaf stalk (not a true stem) is tall (about the same length
as the leaf), smooth, rigid and grooved in front. It is green when young,
but turns dark brown later in the season.
- Leaves - The leaf stalk supports a broad (3 feet long, 3 feet wide), triangular,
dark green, leathery and coarse-textured leaf that often bends nearly horizontal.
The leaf is divided into 3 parts, 1 terminal and 2 opposite. Each of the
leaf parts is triangular and composed of numerous oblong, pointed leaflets,
which are in turn composed of narrow, blunt-tipped subleaflets.
- Fruits & Seeds - A continuous line of spore cases (spore-producing
structures) is formed along the underside edge of leaflets, but the spore
cases are partially or completely covered by inrolled leaf margins and are
difficult to see. Spore cases produce minute, brown spores.
- Biology: Spores of brackenfern are produced August through September.
Brackenfern is one of the earliest ferns to appear in spring or after a
fire. It sometimes forms large colonies of nearly solid stands. In the fall,
it is one of the first plants to be killed by frost, resulting in large
patches of crisp, brown foliage.
- Brackenfern is resistant to many herbicides and is tolerant of various
forms of mechanical control. However, effective control has been obtained
by repeated removal of aboveground growth, which eventually exhausts the
food reserves in the rhizomes.
- Distinguished from other large North Country ferns by the large three
part leaf atop a tall stalk.
- Field Marks
- broad triangular leaf held almost parallel to the ground
- smooth, grooved, rigid stalk about as long as the leaf
- narrowed tip to leaflets
- Global; throughout the world with the exception of hot and cold deserts
- Fossil evidence suggests that bracken fern has had at least 55 million
years to evolve and perfect antidisease and antiherbivore chemicals. It
produces bitter tasting sesquiterpenes and tannins, phytosterols that are
closely related to the insect moulting-hormone, and cyanogenic glycosides
that yield hydrogen cyanide (HCN) when crushed. It generates simple phenolic
acids that reduce grazing, may act as fungicides, and are implicated in
bracken fern's allelopathic activity. Severe disease outbreaks are very
rare in bracken fern.
- Grows on a variety of soils with the exception of heavily waterlogged
sites. Efficient stomatal control allows it to succeed on sites that would
be too dry for most ferns, and its distribution does not normally seem limited
by moisture. Grows best on deep, well-drained soils with good water-holding
capacity, and may dominate other vegetation on such sites.
- Rhizomes are particularly effective at mobilizing phosphorus from inorganic
sources into an available form for plant use. Bracken fern contributes to
potassium cycling on sites and is associated with high levels of potassium.
- In northern climates bracken fern is frequently found on uplands and side
slopes, since it is susceptible to spring frost damage. Fronds growing in
the open or without litter cover are often killed as crosiers by spring
frost damage, since the soil warms earlier and growth begins sooner. The
result is that fronds appear earlier in shaded habitats.
- A shade intolerant pioneer and succession species that is sufficiently
shade tolerant to survive in light spots in old growth forests.
- Light, windborne spores allow colonization of newly vacant areas.
- Despite production of bitter-tasting compounds, chemicals that interfere
with insect growth, and toxic chemicals, bracken fern hosts a relatively
large number and variety of herbivorous insects.
- Competition: Invades cultivated fields and disturbed areas, effectively
competing for soil moisture and nutrients. Rhizomes grow under the roots
of herbs and tree or shrub seedlings, and when the fronds emerge, they shade
the smaller plants. In the winter dead fronds may bury other plants and
press them to the ground. On some sites shading may protect tree seedlings
and increase survival.
- Allelopathy: Bracken fern's production and release of allelopathic chemicals
is an important factor in its ability to dominate other vegetation. Farther
north no allelopathic chemicals are released from the green fronds but are
readily leached from standing dead fronds. Herbs may be inhibited for a
full growing season after bracken fern is removed, apparently because active
plant toxins remain in the soil.
- A fire-adapted species throughout the world. Not merely well adapted to
fire, it promotes fire by producing a highly flammable layer of dried fronds
every fall. Repeated fires favor Bracken.
- Primary fire adaptation is deeply buried rhizomes which sprout vigorously
following fires before most competing vegetation is established. Windborne
spores may disperse over long distances.
- Fire removes competition and creates the alkaline soil conditions suitable
for its establishment from spores
- Fuel loading in areas dominated by bracken fern can be quite high.
- Shrubs: Bunchberry (Cornus
canadensis), Twinflower (Linnaea
- Herbs: Wild Sarsaparilla (Aralia
nudicaulis), Large Leaf Aster (Aster
macrophyllus), Blue Bead Lily (Clintonia
borealis), Gold Thread (Coptis
trifolia), Bedstraws (Galium
ssp.), Oak Fern (Gymnocarpium dryopteris),
Canada Mayflower (Maianthemum canadense),
Bishop's Cap (Mitella nuda), One Flowered Pyrola (Moneses
uniflora), One Sided Pyrola (Pyrola secunda), Rose Twisted
Stalk (Streptopus rosea),
Starflower (Trientalis borealis),
Kidney Leaf Violet (Viola renifolia),
Violets (Viola spp.)
- Mammals: Palatability is usually nil to poor
- Considered so valuable during the Middle Ages it was used to pay rents.
- Used as roofing thatch and as fuel when a quick hot fire was desired.
- The ash was used as a source of potash in the soap and glass industry
until 1860 and for making soap and bleach. The rhizomes were used in tanning
leathers and to dye wool yellow.
- Bracken still used for winter livestock bedding in parts of Wales since
it is more absorbent, warmer, and easier to handle than straw.
- Also used as a green mulch and compost
- Most commonly used today as a food for humans. The newly emerging croziers
or fiddleheads are picked in spring and may be consumed fresh or preserved
by salting, pickling, or sun drying. Both fronds and rhizomes have been
used in brewing beer, and rhizome starch has been used as a substitute for
arrowroot. Bread can be made out of dried and powered rhizomes alone
or with other flour. American Indians cooked the rhizomes, then peeled and
ate them or pounded the starchy fiber into flour. In Japan starch from the
rhizomes is used to make confections. Bracken fern is grown commercially
for use as a food and herbal remedy in Canada, the United States, Siberia,
China, Japan, and Brazil and is often listed as an edible wild plant. Powdered
rhizome has been considered particularly effective against parasitic
worms. American Indians ate raw rhizomes as a remedy for bronchitis
- Bracken fern has been found to be mutagenic and carcinogenic in rats and
mice, usually causing stomach or intestinal cancer. It is implicated in
some leukemias, bladder cancer, and cancer of the esophagus and stomach
in humans. All parts of the plant, including the spores, are carcinogenic,
and face masks are recommended for people working in dense bracken. The
toxins in bracken fern pass into cow's milk. The growing tips of the fronds
are more carcinogenic than the stalks. If young fronds are boiled under
alkaline conditions, they will be safer to eat and less bitter.
- Bracken fern is a potential source of insecticides and it has potential
as a biofuel. Bracken fern increases soil fertility by bringing larger amounts
of phosphate, nitrogen, and potassium into circulation through litter leaching
and stem flow; its rhizomes also mobilize mineral phosphate. Bracken fern
fronds are particularly sensitive to acid rain which also reduces gamete
fertilization. Both effects signal the amount of pollutants in rain water
making bracken fern a useful indicator.
- Fronds may release hydrogen cyanide (HCN) when they are damaged (cyanogenesis),
particularly the younger fronds. Herbivores, including sheep, selectively
graze young fronds that are acyanogenic (without HCN) Lignin, tannin, and
silicate levels tend to increase through the growing season making the plants
less palatable. Cyanide (HCN) levels fall during the season as do the levels
of a thiaminase which prevents utilization of B vitamins.
- Toxicity: Known to be poisonous to livestock throughout the US,
Canada, and Europe. Simple stomach animals like horses, pigs, and rats develop
a thiamine deficiency within a month. Acute bracken poisoning affects the
bone marrow of both cattle and sheep, causing anemia and hemorrhaging which
is often fatal. Blindness and tumors of the jaws, rumen, intestine, and
liver are found in sheep feeding on bracken fern.
- Toxicity: All parts of brackenfern, including rootstocks, fresh or dry
leaves, fiddleheads and spores, contain toxic compounds, and are poisonous
to livestock and humans. Consumption of brackenfern causes vitamin B1 deficiency
in horses, and toxins can pass into the milk of cattle. Young leaves of
brackenfern have been used as a human food source, especially in Japan,
and may be linked to increased incidence of stomach cancer. Humans working
outdoors near abundant stands of the plant may be at risk from cancer-causing
compounds in the spores.
- Facts and Folklore:
It was once thought that, if the spores of the brackenfern were gathered
on St. John's Eve, it would make the possessor invisible.
In the 17th century, live brackenfern was set on fire in hopes of producing
Brackenfern fiddleheads have been used as a food source; however, their
consumption has been linked to various types of cancer in humans.
- Reproduces by spores and vegetatively by rhizomes
- Most regeneration is vegetative. Many have searched for young plants growing
from spores, but few have found them. However, spores do germinate and grow
readily in culture.
- Young plants produce spores by the end of the second growing season in
cultivation but normally do not produce spores until the third or fourth
growing season. A single, fertile frond can produce 300,000,000 spores annually.
Spore production varies from year to year depending on plant age, frond
development, weather, and light exposure. Production decreases with increasing
shade. The wind-borne spores are extremely small. Dry spores are very resistant
to extreme physical conditions, although the germination of bracken fern
spores declines from 95-96% to around 30-35% after 3 years storage. The
spores germinate without any dormancy requirement. Under favorable conditions,
young plants could be found 6 to 7 weeks after the spores are shed. Under
normal conditions the spores may not germinate until the spring after they
- Sufficient moisture and shelter from wind are important factors in fern
spore germination. Bracken fern spore germination appears to require soil
sterilized by fire. On unsterilized soils spores may germinate, but the
new plants are quickly overwhelmed by other growth. Temperatures between
59º and 86º F are generally best for germination, although bracken
fern is capable of germination at 33º-36ºF.
- A pH range of 5.5 to 7.5 is optimal for germination. Germination is indifferent to light quality; it is one of the few ferns that can germinate
in the dark. Despite limitations on spore germination, genotype analysis
in the Northeast indicates that many stands of bracken fern represent multiple
establishment of individuals from spores.
- When spores germinate, they produce bisexual, gamete-bearing plants about
¼" in diameter and one cell thick. These tiny plants have no vascular
system and require very moist conditions to survive. The young spore-bearing
plant which develops from the fertilized egg is initially dependent on the
gametopyte until it develops its first leaf and roots. The first fronds
are simple and lobed. They develop into thin, delicate fronds divided into
lobed pinnae. They do not look like adult plants and are frequently not
recognized as bracken fern. Cultivated plants begin to resemble adult fern
after 18 weeks. The rhizomes begin to develop after there are a number (up
to 10) of fronds and a well-developed root system or in the fifteenth week
of growth under optimal conditions.In the first year rhizomes may grow to
86 inches long. By the end of a second year the rhizome system may exceed
6' in diameter.
- Aggressive rhizome system gives it the ability to reproduce vegetatively
and reduces dependence on water for reproduction. The rhizomatous clones
can be up to 400' in diameter and hundreds of years old; some clones alive
today may be over 1,000 years old.
- Rhizomes have a high proportion of dormant buds. When disturbed or broken
off, all portions of the rhizome may sprout, and plants growing from small
rhizome fragments revert temporarily to a juvenile morphology.
- Shaded plants produce fewerspores than plants in full sun
- Bracken fern is a survivor. The fronds are generally killed by fire, but
some rhizomes survive. The rhizomes are sensitive to elevated temperatures.
During fires the rhizome system is insulated by mineral soil. Depth of the
main rhizome system is normally between 3½" and 12" short
rhizomes may be within 1½" of the surface and some rhizomes may
be as deep as 40".
- Well known postfire colonizer in eastern pine and oak forests. Fire benefits
bracken by removing competition while it sprouts profusely from surviving
rhizomes. New sprouts are more vigorous following fire, and bracken fern
becomes more fertile, producing far more spores than it does in the shade
- Spores germinate well on alkaline soils, allowing them to establish in
the basic conditions created by fire.
- Division most successful method
- Hardy to USDA Zone 3 (average minimum annual temperature -40ºF)
- Characteristically found on soils with medium to very rich nutrients.
- Cultivated and shaded plants produce fewer, thinner but larger fronds
than open-grown plants.
Last Updated on
26 February, 2004