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…

Red valerian was introduced in the 1600s from Europe, but is now naturalised in the UK. Its pinky-red flowers grow from old walls, roadside verges, railway cuttings and cliffs, and provide nectar…

The Sitka spruce was introduced into the UK from North America in the 19th century. It has been widely planted as a forestry tree; look for classic needle-like leaves and pale brown, domed cones…