Originally native to Eurasia and North America, the extreme lightness of its spores has led to it achieving a cosmopolitan distribution.

The large, roughly triangular fronds are produced singly, arising upwards from an underground rhizome, and grow to 0.3–1 metre (1–3+1⁄2 feet) tall; the main stem, or stipe, is up to 1 centimetre (1⁄2 inch) in diameter at the base.

The new growth presents as vertical stalks, coiled and covered in silver-gray hairs, that can be several feet in height before unfurling into fronds.

Though the southern P. esculentum shows little genetic diversity among physically isolated locations, P. aquilinum has distinct groups at the continental scale.

However, evidence of long-distance gene flow was found in samples taken from Hawaii that presented elements of both North American and Asian subspecies of P.

[9] In spite of this, the opinion has been forwarded that the name pertains to the shape of the mature fronds appearing akin to an eagle's wing.

[10] However, medieval scholars, including Erasmus, thought the pattern of the fibres seen in a transverse section of the stipe resembled a double-headed eagle or oak tree.

It can even be aggressive in countries where it is native, such as England, where it has invaded heather (Calluna vulgaris (L.) Hull) stands on the North Yorkshire moors.

[13] Ptaquiloside is known to cause hemorrhagic diseases in ruminants, tumors and hematological problems in non-ruminants, and is correlated with esophageal and gastric cancer in humans.

[20] It has been suggested that selenium supplementation can prevent as well as reverse the immunotoxic effects induced by ptaquiloside from Pteridium aquilinum.

[22] Despite its established toxicity, P. aquilinum's global distribution—it is the fifth most widely distributed common weed species in the world—means that it has a long history of being consumed in many parts of the world.

[26] In Japan, bracken is known as warabi (蕨, ワラビ), and a jelly-like starch made from it is a key ingredient for the chilled dessert warabimochi.

[21] Bracken leaves are used in the Mediterranean region to filter sheep's milk, and to store freshly made ricotta cheese.