The bright green ring-necked parakeet is an escapee and our only naturalised parrot; its success is likely due to warmer winters.

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.

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…

Fennel has feathery leaves and open, umbels of yellow flowers. It was probably introduced by the Romans for culinary use, and is now a naturalised species of verges, waste ground and sand dunes.…