Bracken (Pteridium aquilinum)
| Kingdom | Plantae |
|---|---|
| Phylum | Anthophyta |
| Class | Magnoliopsida |
| Order | Dennstaedtiales |
| Family | Dennstaedtiaceae |
| Genus | Pteridium (1) |
| Size | Leaf length: 30 - 180 cm (occasionally up to 400 cm) (2) |
Very widespread and common (3).
Bracken is a well-known deciduous fern (3); a species that has inspired a rich wealth of folklore in Britain (4). It is easy to recognise by its straw-coloured branching stem, which can reach over four meters in height in good conditions (1). When they first appear in spring, the delicate new fronds which slowly unfurl have been likened to shepherd's or bishop's crooks, or a fiddlehead (5); the young leaves are covered with downy hairs and brown scales. The individual lance-shaped 'leaflets' (pinnae) are 5 to 15 millimetres in length, and brown spore cases (sori) are found around the edges of the undersides of these segments (2). At the base of the fronds there are yellowish hair-like nectaries, which attract ants (4). The fronds die in autumn, taking on a deep golden hue before turning brown (6).
Almost ubiquitous, bracken is extremely common throughout Britain, and its range has increased dramatically during the 20th century. It occurs around the world, with the exception of the Arctic and Antarctic regions (5).
This fern is found in moorland, hill pasture and a variety of other habitats with acidic soils. It particularly thrives on deep loams and sands, but is rare on alkaline soil. It has been found at heights of up to 585 metres, but probably occurs higher than this in some areas (3).
Curled bracken shoots first appear in May and are vulnerable to late frosts at this time (4). This species reproduces by means of spores, which are released from the brown spore-cases on the undersides of the fronds (4). 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 (4). 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).
Not threatened at present.
No conservation action is required for this very common species.
For more information on British plants and their conservation see:
- Plantlife:
http://www.plantlife.org.uk - Botanical Society of the British Isles at:
http://www.bsbi.org.uk
Information authenticated by Professor Rob Marrs of the University of Liverpool
http://www.liv.ac.uk/biolsci with the support of the British Ecological Society
http://www.britishecologicalsociety.org
- Deciduous: a plant that sheds its leaves at the end of the growing season.
- Leaflets: the individual 'leaf-like' parts of a compound leaf.
- Nectaries: nectar-secreting glands, typically located at the base of insect-pollinated flowers. They usually attract insects to flowers, but can also attract seed dispersing insects.
- Rhizome: rhizomes are thickened, branching, creeping storage stems. Although most rhizomes grow laterally just along or slightly below the soil's surface, some grow several inches deep. Roots grow from the underside of the rhizome, and during the growing season new growth sprouts from buds along the top. A familiar rhizome is the ginger used in cooking.
- Spores: microscopic particles involved in both dispersal and reproduction. They comprise a single or group of unspecialised cells and do not contain an embryo, as do seeds.
- Vegetative reproduction: type of asexual reproduction (reproduction without recombination of genetic material) that results in the propagation of plants using only the vegetative tissues such as leaves or stems. The resulting plant is genetically identical to the original plant. A well-known example of this is the reproduction of strawberry plants from 'runners'.
-
National Biodiversity Network Species Dictionary (February, 2003)
http://www.nhm.ac.uk/nbn - Clapham, A.R., Tutin, T.G. and Moore, D.M. (1987) Flora of the British Isles. 3rd Edition. Cambridge University Press, Cambridge.
- Preston, C.D., Pearman, D.A. and Dines, T.D. (2002) The New Atlas of the British and Irish Flora. Oxford University Press, Oxford.
- Freethy, R. (1987) British Ferns. The Crowood Press, Wiltshire.
- Marrs, R. (2004) Pers. comm.
- Mabey, R. (1996) Flora Britannica. Sinclair-Stevenson, London.