This huge gull can be seen around most of the UK's coasts in summer, with some venturing inland in winter.

Red-necked grebes occasionally attempt to nest in the UK, but they're more often seen as winter visitors to sheltered coasts.

Sea lettuce is unmistakeable - most often a bright green and always translucent, it is found on all UK coasts.

An uncommon tree of wet woodlands, riverbanks and heathlands, Alder buckthorn displays pale green flowers in spring, and red berries that turn purple in autumn.

The ragged-edged, purple flower heads of Greater knapweed bloom on sunny chalk grasslands and clifftops, and along woodland rides. They attract clouds of butterflies.