The Sunday Mail
Garden Affair
There are over 200 species of alien weeds in Southern Africa, most of which are threatening to destroy natural ecosystems and affecting agricultural productivity.
An invasive plant is a one introduced from other countries with seemingly good intentions, but later proves to be able to quickly reproduce itself and outgrow local indigenous flora without the direct assistance of people.
Many of these plants were introduced for garden purposes and for commercial purposes such as Wattle and Eucalyptus.
Alien plants are rapidly transforming our indigenous woodlands and forests, but this battle began in our gardens and can be fought in our gardens as well.
The sad reality is that many of these invasive plants are being grown in our gardens to this present day.
Having had the opportunity to visit a number of gardens, I have witnessed first-hand the presence of Lantana camara (cherry pie), Solanum mauritianum (bugweed), Opuntia aurantiaca (jointed cactus), Ricinus communis (castor oil plant), Melia azedrach (syringa) and Jacaranda mimosifolia (yes, our beloved Jacaranda is very invasive and has been declared an invader in South Africa as well).
Most property owners are ignorant of this fact, even using plants like lantana camara as a hedge.
If one travels around Zimbabwe, they will not miss the presence of lantana, which was introduced from South America as an ornamental plant. This plant easily spreads through its fruits, which are consumed by birds and spread over wide distances in their droppings.
Many people even mistake this plant to be Lippia javanica (zumbani), the indigenous herb.
It is the responsibility of every citizen to ensure that they safeguard our heritage for future generations by actively doing something about invasive plants. Just by destroying one plant in one’s yard and planting an indigenous plant instead, the battle is half-won.
A number of plant species have been listed by the Environmental Management Agency in Zimbabwe as invasives and by law any individual who has these plants on their property is required to destroy them.
These are Opuntia aurantiaca, Harisia martini (moonflower cactus), Opuntia fulgida (cactus rosea), Avena fatua (wild oats) and Lantana camara.
There are also aquatic invasives which are also on this list, such as Eichhornia crassipes (water hyacinth), Salvinia molesta (Kariba weed), Salvinia auriculata (water fern) and Azolla filicuiodes (water lettuce).
All these plants have been identified by Government as serious weeds and even though resources are limited, a lot of work is going on to try and bring these plants under control.
The likes of Opuntia fulgida have caused the deaths of livestock in Matabeleland South, particularly in Gwanda and Beitbridge.
The plant has tough thorns which easily injure both humans and animals, attaching itself to the skin or mouths of animals and causing them to starve to death as they are unable to feed.
The cost of monitoring and developing ways of controlling these invasives is staggering.
Biological ways are being investigated, but these have to be thorougly verified as they can also cause serious problems if there is no way of destroying the introduced species.
The only effective way available for us now is mechanical control, which is very expensive in terms of labour since the plants must also be burnt and buried deep to prevent reccurence. It is important that people learn to identify these plants and local assistance is available at Botanic Gardens.
Let us educate our children and as communities form groups that help to destroy these threats to Zimbabwe’s natural beauty.
Only time will tell if we have done something about these alien plants or have left our forests to become extinct.
For further details, contact Andrew Mangwarara on [email protected]
