Pteridium aquilinum / common bracken

Adjectives: clonal, disturbed, edible, fern, fern-like leaves, forest openings, interesting bits, invasive, native, poisonous, toxic

Also known as: bracken, brake, eagle fern, western brackenfern

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Of all the plants on this site with fern-like leaves, this stands apart because it is actually a fern. It is found throughout the world as its extremely light spores circumnavigate the globe on air currents. The only continent not having it is Antarctica.

Common bracken is a herbaceous perennial plant that dies back to the ground in winter. It is one of the few ferns that tolerates full sun. The large, roughly triangular fronds (“leaves”)are arise from an underground rhizome, and grow up to 3 ft tall; the main stem, or stipe, is up to ½ inch in diameter at the base. Because of its rhizomatous growth, it is also clonal and can easily cover any disturbed ground available.

The young fronds, shaped like fiddleheads, emerge in early spring. At that point they are brown and covered in silvery gray hair. Thereafter, whorls of 3 fronds unfold at the tops of the stems. Each is 2 or 3 times compound and generally triangular in outline. The leaf blades are 2 to 4 feet long and 1 to 3 feet wide. The leaflets are also triangular and lobed.

Ferns reproduce by spores rather than by seeds. The spore producing parts are called sporangia and they are in little brown dots, sori, along the undersides of the leaf edges, although they may not be immediately visible because rolled leaf edges cover them. The spores are released in mid to late June, or its equivalent in the Valley.

Bracken grows in pastures, deciduous and coniferous woodlands, and hillsides, and although it prefers acidic soils, it does well enough at places in the Valley. It is considered “highly adaptable” in this way. It readily colonizes disturbed areas, sometimes to the point of being invasive. It also grows on burned-over areas, in woodlands and other shaded places, and on hillsides, in pastures, and ranges in sandy or gravelly soils.

Interesting bits – the specific name, aquilinum, derives from the Latin word for eagle. Supposedly, Linneaus (the originator of binomial nomenclature, i.e. genus and species names) thought that, in cross section, the root looked like an eagle. Alternately, it comes from the “fact” that the mature fronds are sort of shaped like an eagle’s wing. Old time botanists had quite the imagination.

Bracken is edible and the fiddleheads (curled, new fronds) have been widely used as a vegetable in parts of Asia. The rhizomes can be used to make a flour. Please look for real instructions before trying any of this since the shoots used as vegetables also contain a carcinogen, ptaquiloside, that has been linked to stomach cancer in Japan, Wales and Venezuela. Most sites emphasize the toxicity of the plant to humans and to cattle, sheep, horses, pigs and even goats. In grazers, it causes thiamine deficiency. Milk from cows that ate bracken is hazardous to humans.

Investigations on the allelopathic potential of bracken fern in northern Idaho have shown that soil in which bracket grows inhibits the germination and survival of pine seedlings, effectively keeping fern stands pure. Pines are unlikely the only plants so affected.