As its name suggests, Himalayan balsam is from the Himalayas and was introduced here in 1839. It now an invasive weed of riverbanks and ditches, where it prevents native species from growing.

Ivy-leaved toadflax is an introduced species in the UK that has become widely naturalised. Look for creeping along old walls and pavements, and shingle beaches. Its flowers resemble those of…

The Lawson cypress is a large, conical-shaped, evergreen tree that has been introduced into the UK and widely planted in gardens and parks. It has also naturalised along damp banks and woodland…

The London plane tree is, as its name suggests, a familiar sight along the roadsides and in the parks of London. An introduced and widely planted species, it is tough enough to put up with city…

A pretty and distinctive little waterbird, the mandarin duck was introduced from the Far East as its name suggests. Oddly for a duck, it nests in trees, sometimes high above the water.

Tall melilot was introduced into the UK as a fodder crop, but has now become naturalised. It displays golden, pea-like flowers on tall spikes, which are followed by black, hairy seed pods.

An introduced plant, vervain is widely naturalised in the UK. It is a great source of nectar for all kinds of insects and can be seen on rough grassland, waste ground, coastal cliffs and roadside…

The common carp is a very large fish that is popular with anglers due to its size and fighting spirit. It frequents ponds, gravel pits and lakes, but is not native to the UK, being introduced in…

As its name suggests, giant hogweed it a large umbellifer with distinctively ridged, hollow stems. An introduced species, it is an invasive weed of riverbanks, where it prevents native species…

The Holm oak is an introduced species that has been widely planted near the coast and in parkland. It is self-seeding in the south of the UK. Its young leaves are spiny like Holly leaves, and it…

A tall, broad tree of woodlands, roadsides and parks, the introduced horse chestnut is familiar to many of us the 'conker' producing tree - its shiny, brown seeds appearing in their…