Alien Invasive Plants

This series is to inform our local residents about Alien Invasive plants. The articles were published monthly in our local newspaper and we have included as much information as we could find on each one, including the level/category they fall in and information about why they are so damaging to our natural environment.

Many plant species have a strong ability to grow in similar situations but away from their native habitats. The result is that many plants are now found in places where they did not originate. This process of global distribution of plants has been happening for millions of years. In the past 1 000 years – as people have dispersed across the globe – this has speeded up, escalating still further over the past 300 years as modern world travel has developed. In South Africa 198 plant species have been declared weeds and invaders. These plants are termed ‘invaders’ because they spread and displace the indigenous plants.

The major group of offending plant species in southern Africa has been identified, and the Working for Water Programme is active throughout South Africa in clearing alien plant species. Legislation has now been enacted to combat the problem of invasive plant species that threaten the natural flora of the country and, in turn, valuable water resources. Some of the most widespread offending species in random order are Acacia mearnsii (Black Wattle), Saligna (Port Jackson Willow), Cyclops (Rooikrantz), Melanoxylon (Blackwood), Lantana camara (Lantana), Chromolaena odorata (Triffid weed), Solanum mauritianum (Bugweed), Hakea sericea (Silky hakea), Pinus pinaster (Cluster pine), Pereskia aculeata (Barbados Gooseberry) and Melia azedarach (Syringa or Persian lilac).

The question then is ‘Why are invasive alien plants such a problem?’ Apart from displacing the natural flora and therefore impacting negatively on biodiversity they also use more water than the better-adapted natural flora. They also intensify wild fires should these occur. These negative impacts call for concerted action for the control of these invasive alien plants.

The most common invasives are listed below and we will be linking more detailed information to each of these in the future.

Madeira Vine

Mexican Sunflower

Brazillian Pepper

Morning Glory

Yellow Bells

Lantana

Giant Reed

Montanoa

Chromolaena (Triffid Weed)

Indian Shot

Ginger Lilies