The delicate, tube-like, violet-blue flowers of Skullcap bloom from June to September in damp places, such as marshes, fens, riverbanks and pond margins.

The tightly packed, thistle-like purple flower heads of common knapweed bloom on all kinds of grasslands. Also regularly called black knapweed, this plant attracts clouds of butterflies.

Lilac is an introduced species in the UK that can sometimes be found in hedgerows and along woodland edges. Flower spikes appear in spring, beautifully scented and packed with small, lilac-pink…

The Marsh helleborine is a beautiful orchid of fens, wet grassland and dune slacks. Growing in profusion in places, look for reddish stems and white-and-pink flowers.

A tall plant, purple-loosestrife can form dense stands of bright purple flower spikes in wet habitats like reedbeds, fens and marshes.

The bloody henry starfish is normally a bright purply-red colour and is found all around the UK.

The Common fragrant-orchid lives up to its name: it produces a sweet, orangey smell that is very strong in the evening. Look for its densely packed, pink flower spikes on chalk grasslands in…

Look for the star-like, feathery, white flowers of Bogbean in ponds, fens, bogs and marshes. It is so-named because its leaves look like those of broad beans.

The pyramidal orchid lives up to its name - look for a bright pinky-purple, densely packed pyramid of flowers atop a green stem. It likes chalk grassland, sand dunes, roadside verges and quarries…

Common alder can be found along riversides, and in fens and wet woodlands. Its exposed roots provide shelter for fish, and its rounded leaves are food for aquatic insects.