Fern, bristle

Trichomanes speciosum

division: Polypodiophyta

class: Polypodiopsida

order: Filicales

family: Hymenophylaceae

status: Rare, IUCN

range: Azores, Canary Islands, France, Ireland, Italy, Madeira, Portugal, Spain, United Kingdom

Description and biology

The bristle fern has thin, very dry, egg-shaped leaves that measure about 4 to 16 inches long. The leaves are attached to creeping, wiry stems. As the plant matures, structures at the margins (edges) of the leaves harden to form a bristle (point), thus giving the plant its common name.

Ferns reproduce by dispersing spores (tiny, usually one- celled reproductive bodies) instead of seeds. The spore cases, called sporangia (pronounced spor-AN-ja), are located in pockets on the margins of the leaves. Botanists (people specializing in the study of plants) believe the green spores of the bristle fern are dispersed by water (rain and other precipitation) rather than wind.

Habitat and current distribution

The bristle fern is considered vulnerable throughout most of its range. In France and Portugal, it is endangered. The

plant is faring better in Ireland and Spain, where it is listed as rare.

The bristle fern needs a constant source of flowing water. Because the plant has very thin leaves, it is most often found in dark crevices and gullies in deep, narrow, wooded valleys in areas where rainfall is plentiful. It is also found growing in sandstone close to streams and waterfalls.

History and conservation measures

In the nineteenth century, this fern species was sought after to adorn sitting rooms in England and other European countries. Because of its decorative nature, the plant is still quite popular and is commonly grown in botanical gardens.

In the wild, the bristle fern is threatened throughout its range by deforestation (clearing away trees from a forest). In a number of areas in northern Spain, it is also threatened by spreading eucalyptus plantations.

Although the bristle fern is protected under the Bern Convention and the European Union Habitats Directive, no other conservation measures have currently been established.

DID YOU KNOW?

The second most serious threat to native plant species on Earth is introduced or invasive plant species (the first is the loss of habitat). In the United States and Canada alone, over 300 species of invasive plants threaten native ecosystems (ecological community combining all the living organisms and their environment). Half of these plant species were brought by humans to the North American continent to beautify streets and gardens. They have been able to take over the landscape and wipe out creatures from microorganisms to mammals because they lack the natural enemies—insects, microorganisms, and competing plants—they faced back home.

An example of these invasive plants is Eucalyptus trees, which threaten bristle ferns in Spain. Eucalyptus trees are native only to Australia and Tasmania. They have been introduced into temperate (moderate weather) regions around the world because they are decorative and because some species of the tree provide essential oils and tannins (chemicals used to make leather from animal hides). The hard bark and wood of the eucalyptus are also used for various building purposes.