The adder's-tongue fern is so-named because the tall stalk that bears its spores is thought to resemble a snake's tongue. An indicator of ancient meadows, it can be found mainly in…

Our only venomous snake, the shy adder can be spotted basking in the sunshine in woodland glades and on heathlands.

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.

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 alder fly is a blackish invertebrate, with delicately veined wings that it folds over its body like a tent. It can be found near ponds and slow-flowing rivers; the larvae living in the silt at…