INVASIVE WEED SPECIES
 
"The fool learns by experience. The wise man learns by the fool’s experience".
A Chinese proverb.

Nimbin Plant Selection Guide

 

David McMinn

 
Listings are presented of weeds in the Northern Rivers area. Gardeners should avoid planting these species and save themselves much work having to eradicate them from their gardens at a later stage. Even worse, the species can become an invasive weed in the surrounding countryside. This is particularly a problem in rural areas. There are so many beautiful native and non-weedy exotic  species to choose from. It is very unfortunate that gardeners plant weeds, usually out of complete ignorance of the problem they are creating.

Gardeners should learn to identify potential weeds in their area. Early recognition is essential for quick removal of the weed species in the early stages. A few plants are easy to get rid of. Once it becomes firmly established, it will be impossible to eradicate and you will just have to learn to live with the problem.  

If you must plant potential weeds, there may be ways around the problem.

*      Plant seedless varieties of weed species if they are available. The best example is a seedless form of Orange Jessamine (Murraya paniculata). People can plant this variety and still enjoy the perfumed flowers without creating a weed problem. (Birds eat the fruit of this species and disperse the species widely into the local rainforest.)

*      Use the equivalent native species where ever possible. For example, instead of planting Orange Jessamine, use the Native Murraya (Murraya ovatifoliolata). This way the birds can still eat the fruit and you can still appreciate the scented flowers.

*      Each year, strip the unripe seeds from any potential small weedy tree/shrub, thereby preventing the species from spreading. Curry Leaf (Murraya koenigi) is weed candidate, as it suckers profusely and birds relish the fruit. However, it can be placed in a large container and the green, unripe fruit stripped from the tree. Make sure you do this every year.

*      For species with male and female flowers on separate plants, only use male specimens in the garden, so seeds are never produced to create problems. One palm enthusiast planted Chamaedorea palms in the rainforest near his house. They were soon becoming an obvious weed with a potentially severe environmental impact. He pulled out all the seedlings and poisoned all the female plants. Now he can still enjoy his Chamaedoreas without any adverse problems for his rainforest.

NB: Weedy vine species have been covered separately in Exotic Vines: An Environmental Hazard.

The main references used in these listings were:

BFNS Environmental Weeds & Native Alternatives. A Guide to the identification, Control & Replacement. Pamphlet by Bushland Friendly Nursery Scheme. 2004.

Noxious Weeds Guide For the North & Mid North Coast. Pamphlet by the NSW North Coast Weeds Advisory Committee & the Mid North Coast Advisory Committee. 2004.

The listings are primarily of those weed species that gardeners are most likely to consider planting in their gardens. For more comprehensive listings with photos, you may wish to visit the following sites.

North Coast Weeds Advisory Committee.

Association For Growing Australian Native Plants.

Flora For Fauna.

Australian Association of Bush Regenerators.

Weeds Australia

|NON WEEDY VINES

There are several species of native vines that may be grown as a substitute to exotic weedy species.
 

                     
Some weed species are so common that gardeners simply have to live with them and they will not be commented upon: Crofton Weed (Ageratina adenophora), Mist Flower (Ageratina riparia), Tropical Chickweed (Drymaria cordata), & Wandering Jew (Tradescantia albiflora). The main emphasis is given to those species that gardeners may obtain cuttings from friends or unwittingly buy from unscrupulous nursery people.

Mother of Millions (Bryophyllum species) is a succulent spreading herb. Flowers are quite distinctive with various colourings - orange, yellow or red. The flower spikes are held above the foliage. It is poisonous to livestock and should be avoided in country situations.

Apple mint (Mentha rotundifolia) can quickly invade your garden and should not be planted. Other Mentha species are far more useful in cooking and are not so invasive.

Freckle Face (Protasparagus aethiopicus) is a pretty herb with purplish leaves with distinctive pink spots. The flowers are also pinkish. Early elimination will save you the anguish of years of weeding.

Singapore Daisy (Wedelia trilobata) is a spreading groundcover, with distinctive bright yellow flowers.

And the list goes on.......