A delicate, small plant of woodlands and hedgerows, wood-sorrel has distinctive, trefoil leaves and white flowers with purple veins; both fold up at night.

This seagrass species is a kind of flowering plant that lives beneath the sea, providing an important habitat for many rare and wonderful species.

Considered to be one of the prettiest gentians, the Chiltern gentian is a rare plant in the UK. It likes chalk grasslands, its purple, trumpet-shaped flowers blooming from August.

The early gentian is a rare plant that is only found in the UK. It likes sunny, lowland chalk grasslands, its purple, trumpet-shaped flowers blooming in May and June.

The striking black-and-white checks of the marbled white are unmistakeable. Watch out for it alighting on purple flowers, such as field scabious, on chalk and limestone grasslands and along…

As its name suggests, the Dwarf thistle is a low-growing plant that is almost stemless - its purple, thistle-like flower heads growing out of a rosette of spiny leaves.

Bittersweet is a nightshade, so is toxic; its bright red berries may be tempting, but can cause serious illness. Found in hedgerows and gardens, it has purple flowers with yellow stamens.

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.

A common thistle of roadside verges, rough grassland and waste ground, the Musk thistle has large, purple, nodding flower heads that appear in summer. It is attractive to a wide range of insects…