Pteridium
Bracken
Bracken
Wikipedia links: Monilophytes > Polypodiales > Dennstaedtiaceae > Pteridium
Other links:
Species: D esculentum
Common name: Bracken
Conservation status: . . .
Etymology:
From pteron, feather or wing, alluding to the shape of the leaves
The word bracken is of Old Norse origin, related to Swedish bräken and Danish bregne, both meaning fern
Spores:
Like other ferns, brackens do not have seeds or fruits, but the immature fronds, known as fiddleheads, are sometimes eaten, although some are thought to be carcinogenic
Leaves:
Brackens are noted for their large, highly divided leaves
Stem & branches:
Roots:
Habit:
Habitat:
Distribution:
They are found on all continents except Antarctica and in all environments except deserts, though their typical habitat is moorland
The genus probably has the widest distribution of any fern in the world
Species:
World: ~ 10
Australia: . . .
Additional notes:
Taxonomy
Bracken (Pteridium) is a genus of large, coarse ferns in the family Dennstaedtiaceae
Ferns (Pteridophyta) are vascular plants that have alternating generations, large plants that produce spores and small plants that produce sex cells (eggs and sperm)
In the past, the genus was commonly treated as having only one species, Pteridium aquilinum, but the recent trend is to subdivide it into about ten species
Description and biology
Evolutionarily, bracken may be considered one of the most successful ferns. It is considered highly invasive, and can survive in acid soils
Bracken, like heather, is typically found in moorland environments, and is commonly referred to by local populations in the north of England as 'Moorland Scrub'
It is also one of the oldest ferns, with fossil records over 55 million years old having been found
The plant sends up large, triangular fronds from a wide-creeping underground rootstock, and may form dense thickets
This rootstock may travel a metre or more underground between fronds. The fronds may grow up to 2.5 m (8.2 ft) long or longer with support, but typically are in the range of 0.6–2 m high
In cold environments, bracken is deciduous and, as it requires well-drained soil, is generally found growing on the sides of hills
Fern spores are contained in structures found on the underside of the leaf called sori
The linear, leaf-edge pattern of these in bracken is different from that in most other ferns, where the sori are circular and occur towards the centre of the leaf.
Distribution wrt UK
Pteridium aquilinum (bracken or common bracken) is the most common species with a cosmopolitan distribution, occurring in temperate and subtropical regions throughout much of the world
It is a prolific and abundant plant in the moorlands of Great Britain, where it is limited to altitudes of below 600 metres. It does not like poorly drained marshes or fen
It has been observed growing in soils from pH 2.8 to 8.6.
Exposure to cold or high pH inhibits its growth
It causes such a problem in invading pasturelands that at one time the British government had an eradication programme
Special filters have even been used on some British water supplies to filter out the bracken spores
Bracken is a characteristic moorland plant in the UK which over the last decades has increasingly out-competed characteristic ground-cover plants such as moor grasses, cowberry, bilberry, and heathers, and now covers a considerable part of upland moorland
Once valued and gathered for use in animal bedding, tanning, soap and glass making, and as a fertiliser, bracken is now seen as a pernicious, invasive, and opportunistic plant, taking over from the plants traditionally associated with open moorland and reducing easy access by humans
It is toxic to cattle, dogs, sheep, pigs, and horses, and is also linked to cancers in humans
It can harbour high levels of sheep ticks, which can pass on Lyme disease
Grazing provided some control by stock trampling, but this has almost ceased since the 2007 foot-and-mouth disease outbreak reduced commercial livestock production
Global climatic changes have also suited bracken well and contributed to its rapid increase in land coverage
Bracken is a well-adapted pioneer plant which can colonise land quickly, with the potential to extend its area by as much as 1–3% per year
This ability to expand rapidly at the expense of other plants and wildlife can cause major problems for land users and managers
It colonises ground with an open vegetation structure, but is slow to colonise healthy, well managed heather stands
Bracken presents a threat to biodiversity
Many plant species occur only on upland moorland, tied to unique features in the habitat
The loss and degradation of such areas due to the dominance of bracken has caused many species to become rare and isolated
Sources of information: