The European larch was introduced into the UK from Central Europe in the 17th century. Unusually for a conifer, it is deciduous and displays small, greeny-red cones on brittle twigs.

Although introduced by humans, the fallow deer has been here so long that it is considered naturalised. Look out for groups of white-spotted deer in woodland glades.

The grey squirrel was introduced into the UK in the 1800s. It provides an easy encounter with wildlife for many people, but can be damaging to woodlands and has contributed to the decline of the…

The Norway spruce was introduced into the UK from Scandinavia in the 16th century. It is familiar to us all as the 'original' Christmas tree and displays hanging, reddish-brown, oblong…

Pineappleweed is an introduced species that has become a widespread 'weed' of disturbed ground, such as pavements and roadsides and gardens. It has feathery leaves and yellow flower…

The White-clawed crayfish is a freshwater, bronze-coloured crustacean with pale undersides to its claws - hence the name. It is under threat from an invasive and introduced species of crayfish.…

Buddleia is a familiar shrub, well-known for its attractiveness to butterflies. It is actually an introduced species, however, that has become naturalised on waste ground, railway cuttings and in…