Running the Farm : Weedbuster's wicked weed Series
Originally from Brazil, the exotic sounding alligator weed is a dangerous invader sneaking into wetlands, rivers and even subdivisions around the North Island. It's a hollow-stemmed "super weed" with small clover-like flowers and lush, oval leaves. Luckily it doesn't spread by seed in New Zealand, but every small fragment can form a new plant. 
This macho Mediterranean creeper is a hard one to get control of once it is established. It was originally planted for its glossy green or variegated green and yellow, or green and white, leaves and striking blue-violet flowers, and unfortunately it is still found in many gardens and along roadsides where it has been dumped or planted. 
This tough South African import is not the sort of immigrant that our environment needs. With its shiny, leathery, dark-green leaves and umbrella shaped clusters of purplish-blue or white flowers, it has won the hearts of many a gardener who wants a hardy plant for difficult areas with poor soil.
Despite its silver coated leaves, this creeping groundcover is no little treasure. Aluminium plant, also known as artillery plant, is often found in gardens growing in the cooler areas around trees and shrubs. It has pleasant smelling, mint-like leaves, square, purplish stems, and hairy, soft lemon-yellow flowers in summer. 
A very fast growing, though thankfully short lived tree - popping up on cliffs, banks, hillsides, slips and cuttings. One of the few flowering trees around in winter, brush wattle is conspicuous now with greenish-yellow bottlebrush-like flowers. It is reasonably common in the North Island, though rarer in the south.
This smelly South American scrambler is happy sneaking its way through, under and over whatever plants and trees get in its way. It has brittle stems and hairy oval leaves that are wrinkled with toothed edges. All parts of the plant are poisonous to stock.
This large, luscious Tahitian interloper has leathery deep green arrow-shaped leaves and thick trunk-like stems, supported by a fleshy underground root system. Fragrant creamy-yellow to orange flower spikes develop into scarlet or orange berries. Leaves and stems ooze a sticky milky sap if crushed or cut. 
Originally widely used as a hedging plant, Chinese privet was planted extensively throughout towns and rural areas as hedging. It has small, glossy, bright green leaves with smooth edges, and it produces tiny, smelly, creamy flowers from October to January, followed by bluish or purplish-black berry-like fruit with a powdery coating. 
This Chinese climber is loved for its strong scent and delicate white flowers, and hated for its tough, vigorous, twining stems that rapidly swamp everything it grows over. 
Like a giant version of the much loved busy Lizzies, shrub balsam can reach up to 2m in height.
This vine from Asia first established in the wild in New Zealand as early as 1926.
This exotic, ginger-scented perennial with massive, taro-like rhizomes close to the surface has shiny leaves, and cream coloured flowers overlapping in cone-like clusters from May to June. It is sometimes mistaken for a canna lily.