Honeysuckle (Lonicera japonica)
Japanese honeysuckle, a vigorous, woody scrambler, has long wiry stems. The plant has escaped from gardens and is abundant in Auckland City and northern Hawke’s Bay. It is a problem in native forest reserves, where it smothers trees and shrubs. In the USA this weed can overrun entire forests.
Jasmine (Jasminum polyanthum)
Jasmine is a fragrant, evergreen climber that twines up trees and shrubs. It suffocates native plants along forest margins and in broken bush, from Gisborne northwards. South of Gisborne, jasmine is a well-behaved garden plant. Charles Darwin saw it (as well as gorse and honeysuckle) growing in missionaries’ gardens in Northland in 1835, but it was not reported growing wild until 1980.
Old man’s beard (Clematis vitalba)
Introduced from Europe as a garden plant, old man’s beard was first noticed growing wild in New Zealand in 1940. Also known as traveller’s joy, this woody, deciduous climber scrambles up and over shrubs and trees, its thick stems sometimes growing 30 metres long. Masses of fluffy seeds are released in autumn, and plants can sprout from fragments of stem.
This aggressive weed takes hold in forest gaps and along the margins of forest and scrub reserves, especially on recently disturbed sites. It overwhelms its host trees, notably in the southern half of the North Island, Nelson, Marlborough, Buller, Kaikōura and Canterbury, and especially near Taihape, where a single plant can cover an area the size of a tennis court. Old man’s beard grows throughout both islands except in Westland and Fiordland, and on Stewart Island and the Chatham Islands. Property owners are legally obliged to remove it.
Morning glory (Ipomoea indica)
A relative of the kūmara, morning glory is abundant in many tropical countries and was first reported growing wild in New Zealand in 1950. It is a vigorous purple-flowered climber with stems, sometimes hundreds of metres long, that swarm up native trees. It does best in sunny, frost-free places, and blooms year round in northern New Zealand. Most plants never produce seeds, but in 1996 one Bay of Plenty specimen had large amounts of seed, and seedlings nearby.
Wild kiwifruit (Actinidia deliciosa)
A kiwifruit vine can grow 20 metres high and cover 1,000 square metres in 30 years. The plant has escaped cultivation to grow wild along bush margins in the Bay of Plenty, where it chokes native trees. The species can also be found in the Marlborough Sounds.