Family: Dennstaedtiaceae

Common name: Bracken fern

E-flora BC: https://linnet.geog.ubc.ca/Atlas/Atlas.aspx?sciname=Pteridium%20aquilinum

Wikipedia: https://en.wikipedia.org/wiki/Pteridium_aquilinum

Bracken fern is distributed around the world, occurring almost everywhere except for in tropical and arctic regions. In our region, it tolerates a range of habitats and is often a bit weedy in nature. It tends to invade clearcuts and other open or disturbed sites. In moist sites, individual fronds (leaves) can grow to several meters tall, in dry sites, leaves might be around 40 cm tall.

The general impression of bracken fern is usually light-green, fluffy foliage – feathery leaflets borne on slender leaf-stalks.

A dense stand of bracken fern. Photo credit: Bjorn S via Flickr
Tall specimens of bracken fern in a moist, favourable site.

Individual compound leaves of bracken fern are triangular in shape. Note the broad base and narrowing toward the top:

These bracken specimens are growing in a less favourable site than those in the photograph with the person above. These ones are only about 60 cm in height, rather than 2 m tall.
The leaf stalk (stipe) is slender and hairless. The leaflet margins are rolled under. Photo credit: Douglas Fraser

Bracken spreads mostly by branching and extending its underground stem (rhizome), from which it sends up new leaves. It can quickly cover a large area in this way. Sometimes, you will come across spore-bearing leaves within a stand of bracken. Unlike the other ferns discussed on this site (Athyrium filix-femina, Polypodium glycyrrhiza and Polystichum munitum), the sori of bracken fern are continuous with the leaflet margin, rather than distributed as dots on the underside of the leaf:

Notice the rusty-coloured sori lining the rolled under leaflet margin.
Close-up of a spore-bearing leaflet – you can discern the individual sporangia.

Sometimes, people can get bracken and lady fern mixed up. Both have light-green, delicate foliage. The quickest way to distinguish between them is to look at the leaf shape, as shown in the diagram below. If it’s triangular, then it is bracken fern. If it is diamond shaped, then it is lady fern.

Simplified shape of bracken fern leaf on the left, and lady fern leaf on the right.
Bracken fern leaf on left, lady fern leaf on right. An additional characteristic is to look at the leaf stalk; bracken fern has a smooth leaf stalk, lady fern has a flaky leaf stalk. Photo credit: Hitomi Kimura

Another way to distinguish bracken and lady fern is how the whole plants grow. With bracken fern, leaves emerge singly from the ground, often forming a large stand. With lady fern, leaves are clustered together as they emerge from a central point.