Pteridium aquilinum (BIS-Fogo)

Pteridium aquilinum

Summary ⁸

Pteridium aquilinum (bracken, brake or common bracken), also known as "eagle fern," is a species of fern occurring in temperate and subtropical regions in both hemispheres. The extreme lightness of its spores has led to its global distribution.

Biology ⁹

Curled bracken shoots first appear in May, and are vulnerable to late frosts at this time (5). This species reproduces by means of spores, which are released from the brown spore-cases on the undersides of the fronds (5). It can also spread by vegetative reproduction, from a subterranean creeping storage organ known as a rhizome (2). When cut in half, the rhizome is said to display a pattern reminiscent of an oak tree, or outspread eagle wings (which may account for the specific name, aquila, which means eagle). It was also believed that letters could be seen in the patterns inside a rhizome; these were thought to show the initials of a future spouse (5). This fern also became associated with invisibility, although the reason is not entirely clear. It has been suggested that the lack of flowers may have fuelled the association; the mysterious absence of flowers was once thought to be magical (6). This species has been put to a wide range of practical uses, as manure, mulch, tinder, and fuel; in 18th Century Scotland it was burned to obtain potash needed for glass and soap manufacture, and it was (and still is in some areas) used as a bedding for livestock (6). One of its main uses, however, was as a packaging material (6). As these applications have declined, bracken cutting has ceased in many areas, and the species has spread dramatically as a result (6). Although livestock tend to avoid bracken, as it is extremely toxic, in dry years when there is very little else to eat livestock may browse on bracken, often with fatal results (6).