Synonymy

Pteridietum aquilinae auct. angl.

Constant species

Festuca ovina, Galium saxatile, Potentilla erecta, Pteridium aquilinum.

Physiognomy

Pteridium aquilinum is a characteristic member of a variety of vegetation types, being especially important as a constant in the field layers of a number of woodland, scrub and underscrub communities, often occurring there in abundance, and locally prominent also among some heaths and grasslands. In the Pteridium-Galium saxatile community, however, it is the sole dominant in the very familiar acidophilous bracken vegetation, occurring always here with a cover of more than 25%, and being overwhelmingly abundant in many stands, the fronds sometimes reaching 2 m or more in height and growing so thickly as to be virtually impenetrable by the middle of the season.

The annual crop of foliage begins to appear in spring, the fronds arising individually from the deep and farcreeping rhizomes and emerging, pale green and coiled like clenched fists, as Page (1982) so memorably puts it, through what is often a very thick mat of litter. Once up, the fronds expand fairly quickly, although it is usually mid-June in the south and at lower altitudes, and July on higher ground and to the north, before the canopy is fully developed. There is thus some opportunity for a vernal contribution from the associated flora before the leathery and dark green bracken foliage of mid-summer begins to cast its characteristic deep shade. With the first frosts of autumn, the fronds rapidly die, often snapping over mid-way and eventually subsiding into the slowlydecaying litter layer. The changing tints of the autumn bracken, through yellow-green to the striking rusty brown, provide much delight in their contribution to the landscape, and the colour of the dead fronds marks out stands of this vegetation right through the winter, should they by any chance have been missed before.

Within this general phenological pattern, there is much variation in the growth of Pteridium here, and in the structural contribution which it makes to particular stands of the community through the year and from one season to the next.