The Sitka spruce was introduced into the UK from North America in the 19th century. It has been widely planted as a forestry tree; look for classic needle-like leaves and pale brown, domed cones…

Look for the round, cottony, purple flower heads of the Woolly thistle on chalk and limestone grasslands in summer. It is mainly found in Southern England.

Growing in tufts, Crested dog's-tail is a stiff-looking grass, with a tightly packed, rectangular flower spike. Look for it in lowland meadows and grasslands.

Cock's-foot is a common, tussocky grass of grasslands, woodland rides and cultivated ground - its fluffy, pinky-beige flower heads are quite distinctive.

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.

Pineappleweed is an introduced species that has become a widespread 'weed' of disturbed ground, such as pavements and roadsides and gardens. It has feathery leaves and yellow flower…