The knopper gall wasp produces knobbly red, turning to brown, growths, or 'galls', on the acorns of Pedunculate Oak. Inside the gall, the larvae of the wasp feed on the host tissues, but…

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…

The holm oak is an introduced species that has been widely planted near the coast and in parkland. It is self-seeding in the south of the UK. Its young leaves are spiny like holly leaves, and it…

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…

With brown-and-orange markings, the drone-fly looks like a male honeybee, but is harmless to us. This mimicry helps to protect it from predators while it searches for nectar in gardens and urban…

Introduced from Japan in the 19th century, Japanese knotweed is now an invasive non-native plant of many riverbanks, waste grounds and roadside verges, where it prevents native species from…

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.

These non-native limpets arrived from America in the 19th century and are now widespread in the UK. They form stacks and have a specially adapted shell which, when flipped upside down, looks like…

With black-and-yellow markings, the hornet robberfly looks like its namesake, but is harmless to us. This mimicry helps to protect it from predators while it perches in the open, waiting for its…