Other invasive weeds in New Zealand



Clematis vitalba (Old Man's Beard) is a fast growing, deciduous climber. Seedlings have one to three leaflets and the mature plant has five leaves. The flower appears in summer and early autumn, is creamy white in colour and is perfumed. The characteristic feathery seed heads give this climber its name and appear from autumn to spring. The vines have six strong longitudinal ribs. Older stems have pale brown stringy bark with longitudinal furrows.

Old Man's Beard is a vigorous plant. Each stem can produce up to ten metres of new growth in a season, and stems trailing along the ground can root at each stem node to produce new plants. Each plant can produce more than 100,000 seeds in a year, mainly spread by wind and water.

Old Man's Beard is capable of smothering large areas of native forest. It scrambles and climbs over other vegetation including tall trees, denying them the light they need for growth and even breaking branches with the sheer weight of the vines. This creeper prevents regeneration in forest gaps by blocking light to the ground and taking over where other species could establish.

By killing native woody plants, Old Man's Beard destroys food sources for native species, including birds, lizards and insects. The creeper affects the ecosystem by killing trees and increasing the amount of dead material in forests.

 

The banana passionfruit, Passiflora mollissima and its close relative Passiflora mixta, are vigorous climbers, often growing several metres in height. The leaves are a shiny green with clearly defined veins, the flower is large, pink and green petalled with a yellow and white centre. The fruit is yellow-orange when ripe and contains a sweet edible orange-coloured pulp with black seeds.

The banana passionfruit is capable of smothering forest margins and forest regrowth with its dense growth of leafy vines. It is a particular problem in parts of Nelson and Marlborough.

 

FOLLOWUP

 

1. Look elsewhere on the intranet, and find a picture of a clematis seed head, so you can see how the seeds might spread so easily.

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