So-named because its gnarled trunk can split as it grows, the Crack willow can be seen along riverbanks, around lakes and in wet woodlands. Like other willows, it produces catkins in spring.

A summer visitor, the willow warbler can be seen in woodland, parks and gardens across the UK. It arrives here in April and leaves for southern Africa in September.

Common mallow is a handsome 'weed' of waste ground, roadside verges and gardens. Its deep pink, stripey flowers provide nectar for insects throughout the summer.

Although introduced by humans, the fallow deer has been here so long that it is considered naturalised. Look out for groups of white-spotted deer in woodland glades.

Musk mallow has pretty pink flowers that can be seen along roadside verges, hedgerows and field margins in summer. It lives up to its name, producing a delicate, musky smell that increases indoors…

A recent colonist to South East England, the metallic-green Willow emerald damselfly spends much of its time in the willow and alder trees that overhang ponds, lakes and canals.

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…

Common laburnum is an introduced species, planted in parks and gardens. It is most recognisable in flower - its hanging bunches of yellow blooms giving it the name 'Golden rain'. It is…

Fennel has feathery leaves and open, umbels of yellow flowers. It was probably introduced by the Romans for culinary use, and is now a naturalised species of verges, waste ground and sand dunes.…

Eyebright has small, white flowers with purple veins and yellow centres. It likes short grasslands, from clifftops to heaths, and is one of a number of species and hybrids that are hard to tell…

Nudibranchs, also known as sea slugs, are much like their land-based relatives that you may spot in your garden. But, unlike your regular garden slug, the nudibranch can incorporate the stinging…