Ground-elder was likely introduced into the UK by the Romans and has since become naturalised. A medium-sized umbellifer, it is an invasive weed of shady places, gardens and roadsides.

Plaice is a common sight all around our coasts - if you can spot it! They are extremely well camouflaged against the seabed and can even change colour to better match their surroundings.

Often spotted in large flocks, the fieldfare is an attractive thrush. It is a winter visitor, enjoying the feast of seasonal berries the UK's hedgerows, woodlands and parks have to offer.

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.

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…