This striking duck was introduced to the UK and is now established as a breeding bird in England.

Sika deer were introduced to the UK in the 19th century. They are native to eastern Asia.

The nodding, blue bells of the harebell are a summer delight of grasslands, sand dunes, hedgerows and cliffs. They are attractive to all kinds of insects, too.

Pellitory-of-the-wall is a small to medium-sized herb that frequently grows from cracks in old stone walls, pavements, cliffs and banks, and churches and ruins.

Egyptian geese were introduced to Britain from Africa. They are now widespread in southern England.

Europe's largest frog is not naturally found in the UK, but was introduced to Kent and has spread throughout the southeast.

Horseradish is used as a well-loved condiment. This member of the cabbage family is actually an introduced species in the UK, but causes no harm in the wild.

Sometimes called 'Wild spinach', Sea beet can be cooked and eaten. It grows wild on shingle beaches, cliffs and bare ground near to the sea, as well as in saltmarshes.

The upright, blue flower spikes of Viper's-bugloss can be spotted on chalk grassland, sand dunes, cliffs and banks. Its spotted stem is thought to resemble a viper.