Triangular fronds emerge singly from a deep rhizome, never as a shuttlecock, and are divided three times over
Bracken — the shuttlecock crowns of other big ferns give them away at once.
Nature · Ferns, grasses & other plants
Bracken
Deciduous fern · fronds to 2–3 m
Pteridium aquilinum — Dennstaedtiaceae
Bracken is the commonest fern in Britain and among the most widespread vascular plants on Earth, found on every continent except Antarctica. It spreads by deep, far-running underground rhizomes rather than by spores, so it advances across hillsides, heaths and open woodland as a single clone, shading out almost everything beneath it. Its fronds unfurl late in spring and turn foxy brown at the first frost, colouring whole uplands.
How to spot them
- ▸Large triangular fronds, divided three times over, held roughly horizontally like a small canopy
- ▸Fronds arise singly from the soil, never in a shuttlecock crown — the giveaway against other big ferns
- ▸Spore cases run in a continuous line under the rolled-under leaf margin, not in dots on the surface
- ▸Turns rust-brown after the first frosts and collapses, while evergreen ferns stay green
- ▸Dominates acid heath, hillside and woodland ride in continuous waist-high stands
How to know it
Its Latin species name means 'eagle-like', from a shape said to be seen in the cut rhizome
Pteridium aquilinum; the genus name is simply from the Greek for fern.
Contains ptaquiloside, a carcinogen, and thiaminase, which destroys vitamin B1 in horses and cattle that graze it
Bracken — hence the staggers and blindness of poisoned stock.
Whole upland hillsides turn foxy red-brown at the first autumn frost as this one species collapses
Bracken.
Spore cases sit in a continuous line beneath the inrolled edge of each leaflet, under a false indusium
Bracken — though in Britain it seldom sets viable spores, spreading instead by rhizome.
Young croziers are eaten in Japan as warabi, and the rhizomes were once ground for famine flour
Bracken — a practice now discouraged on health grounds.
Once cut in quantity for animal bedding and burnt for potash, which kept its Victorian cover far below today's
Bracken.
Quick-fire facts
- •One of the most widely distributed vascular plants in the world, absent only from Antarctica and the driest deserts
- •The epithet aquilinum means 'eagle-like', variously explained by the pattern in a cut rhizome or the outline of the frond
- •A fern, so it has no flowers and no seeds; it reproduces sexually by spores and spreads by rhizome
- •Rhizomes can run metres a year and lie deep enough to survive burning, which is why bracken is so hard to clear
- •Contains ptaquiloside, a recognised carcinogen, and thiaminase, which breaks down vitamin B1
- •Bracken litter shelters the caterpillars of fritillary butterflies, so total clearance is not always a conservation gain
- •Belongs to the family Dennstaedtiaceae, not the Dryopteridaceae or Polypodiaceae of most other British ferns
- •Fronds can reach 2–3 m in sheltered ground, making it the largest British fern
Drill it — 7 cards
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Sources
- Woodland Trust — Bracken (Pteridium aquilinum)