THE TOP 5

Common plants that turn out to be invasive weeds.

1 Prickly Pear Cactus Native to the Americas, this fearfully impressive plant is well-suited to harsh deserts – and a spiky threat to our coastal dunes.

2 Ivy An evergreen climber that looks lovely in Europe but is bad news in our bush. There it can spread along the ground or climb trees, dominating woodlands and reducing native regeneration.

3 Pampas grass Pointing upright with a dense, fluffy top, pampas look like our droopier native toetoe, but compete against it. Once seedlings are established, they can form dense, often impenetrable clumps.

4 Fairy crassula A common garden succulent with fleshy leaves and clusters of small, pale pink flowers in spring. In the wild it competes with native species, forming dense mats.

5 Arum lily This clumping lily has distinctive large white flowers and wide leaves. It loves swamps and regenerating ex-pasture where it crowds out native plants.