Pteridium aquilinum is a herbaceous fern that can reach a height of 120-150 cm. It is native to Eurasia and North America. The plant fern reproduces by spores and rhizomes.
It can be identified by its deep, thick spreading rhizomes and large, finely divided, triangular fronds that bear a line of sori under their reflexed margins.
Eagle Fern Classification
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Tracheophyta
- Class: Polypodiopsida
- Order: Polypodiales
- Family: Dennstaedtiaceae
- Genus: Pteridium
- Species: Pteridium aquilinum
- Varieties: Pteridium aquilinum var. aquilinum, pteridium aquilinum var. champlainense, Pteridium aquilinum var. decompositum, Pteridium aquilinum var. latiusculum, Pteridium aquilinum var. pseudocaudatum, Pteridium aquilinum var. pubescens
- Common Names: Bracken, Northern Bracken Fern, Western Brackenfern, European Fern, Pasture Brake, Hog Brake, and Brake
Nativity and Distribution
Common Bracken is native to Eastern Asia, Europe, and North America. However, the fern has achieved an almost cosmopolitan distribution. This means it is easily adaptable to a range of climatic conditions and can be found in regions across both hemispheres except Antarctica.
Physical Characteristics
- Leaves: Large, triangular fronds, typically 30-100 cm long
- Roots: Deep, long-living rhizomes
P. aquilinum is a herbaceous perennial fern that can grow up to 1.2-1.5m tall. It can be identified by its deep, thick spreading rhizomes and large, finely divided, triangular fronds, which seem nearly parallel to the ground and bear a line of sori under their reflexed margins.
Leaves are robust, glabrous or pubescent, triangular, about 30-100 cm long. They arise singularly from the underground rhizome, along with a stipe that’s 1 cm wide at the base.
The blades are finely divided into pinnae, which in turn, divide into pinnules. The leaves typically angle back, seemingly appearing parallel to the ground. Spores are present in the fertile fronds, in a nearly unbroken line of sori along the leaflet margins.
Rhizomes are about 5 cm wide and grow about 3.5m deep underground. The individual rhizomes can live for over 70 years.
Reproduction, Dispersal, and Life Cycle
- Life Cycle: Perennial
- Seeds: Produces spores
- Climate: Temperate and subtropical climates
- Dispersal: Wind, Animals, and human activity
Eagle fern is a perennial plant that thrives in temperate and subtropical regions. It is among the most widespread fern species in the world and reproduces by spores and rhizomes.
The spores are formed on the underside of the fronds in nearly unbroken narrow bands called sori. Spores are typically dispersed by wind, but they can also be moved by animals and human activities like tillage and soil movement.
Once ideal conditions are achieved, the spores grow into gametophytes that, once fertilized, produce new sporophyte ferns.
However, Bracken’s primary propagation method is by vegetative means, where new fronds emerge from the rhizomes.
Commonly called fiddleheads, the young coiled fronds emerge from the underground rhizomes in spring. During summer, they uncoil and fully expand to produce the spores on the underside of the leaflets.
In the fall, the fronds turn brown and die back. The rhizomes remain active underground, allowing for new frond-sprouting year after year.
Since they collectively regrow from the same rhizome network, the fern forms dense colonies of genetically identical fronds.
Common Bracken prefers well-drained soils with high water-holding capacity and acidic soils. You’ll typically locate it in riparian lands, roadsides, meadows, deciduous woodlands, pastures, and hillsides.
Similar Plants
- Athyrium filix-femina
- Dryopteris filix-mas
- Matteuccia struthiopteris
Uses
- Young bracken shoots are eaten raw or cooked as a vegetable, especially in Asia.
- It is used as mulch and as livestock winter bedding in Wales because it is highly absorbent and warm.
- Parts of the plant, like the young shoots and roots, have been used as medicinal treatments for various ailments, including arthritis, cancer, wounds, stomach pains, and colds.
- The leaves are used to filter milk and store ricotta cheese in the Mediterranean region.
- The ferns are used as a durable thatch.
- The fronds are used to filter palm oil and wine.
- It is a potential source of biofuel and insecticides.
Impact on Farms and Environment
While Pteridium aquilinum can adapt and grow in numerous environments, it is also an opportunistic fern and will likely grow in abandoned or unmanaged farms rather than active cropping systems.
Here, it can form large canopies if left unchecked and may become a troublesome weed on fallow lands.
In rare cases where the soil conditions are ideal, it can invade gardens and fields, competing for important resources and light. The rhizomes can grow under the roots of desirable plants, and the fronds may shade out smaller plants. Additionally, it becomes difficult to control due to the underground rhizomes.
Since it prevalently invades pastures, it can cause livestock toxicity. The fern produces a carcinogen called ptaquiloside that causes hemorrhagic diseases and even death in ruminants.
The human consumption of Bracken either as a vegetable or in the form of ptaquiloside-contaminated milk and meat has also been linked to certain cancers, such as esophageal and stomach cancers.
In other habitats, such as coniferous forests and woodlands, it can easily colonize new areas through the dispersal of spores, dominating native vegetation in such areas.
Common Bracken has been documented to pioneer in harsh environments such as cooled lava slopes and recently burned forest floors.
Control
- Mechanical control: Repeated cutting and digging of the rhizomes
- Chemical control: Repeated applications of asulam, glyphosate, picloram, and dicamba
Cutting is a viable option if done at the right time. Cut the fronds in early summer and allow the emergence of new fronds before recutting to deplete the rhizome resources. Follow up with digging the rhizomes out.
Herbicide applications are more effective when combined with cutting. Cut the ferns and spray asulam herbicide. Once the fronds are dead, cut them off.
Apply herbicides like glyphosate, dicamba, picloram, 4-CPA, or dichlobenil to the rhizomes repeatedly to reduce the starch stores and to achieve eventual eradication.
Ensure to read and follow herbicide application instructions. If you’re unsure of the best combination to use or how to apply any herbicide, consult a local extension expert.
Lead Editor for Insight Weeds.