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.

Despite its name, Ground-ivy is actually a member of the dead-nettle family. It is a clump-forming, aromatic plant that likes woodlands, hedgerows and damp places.

This stocky wader is mostly a winter visitor to the UK, where it can be found on rocky, seaweed-covered coasts, often with groups of turnstones.

The Migrant hawker is not a particularly aggressive species, and may be seen feeding in large groups. It flies late into autumn and can be seen in gardens, grasslands and woodlands.

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.

The vast, green mats that sometimes cover the surface of still water, such as ponds, flooded gravel pits and old canals, are actually Common duckweed. A tiny, single plant, it groups together to…

Crosswort gets its name from the position of its leaves - they surround the stem in groups of four, making a cross shape. The tiny, yellow flowers sit atop these crosses and bloom from April to…