Water hyacinth got into Pagasvlei in Constantia, becoming a serious invasion which covered the entire water body. It took two seasons to remove it from this area using invasive species work teams.

Cape Town - David in Vancouver is selling mail order water hyacinth (Eichhornia crassipes) for $3 (about R24) a bunch. For $8 you can buy snake grass (Equisetum hyamale) from Montana, and for £9.50 you can have three Spanish brooms (Spartium junceum) dispatched to you from the UK’s largest wholesale nursery.

You can also buy dragonfly nymphs from Ohio, and an Australian bearded dragon lizard from an online exotic pet shop in Britain for £27.

The mail order trade in flora and fauna on the internet is growing exponentially, and its potential impact on local biodiversity is of great concern to governments worldwide. In July, senior invasive species experts from various countries, including SA’s Dr Guy Preston, met in Switzerland to discuss the burgeoning international trade in invasive species, and to develop strategies to reduce the risks to regional biodiversity.

Discussions at an international level are mirrored locally. Stellenbosch academic Professor Dirk Bellstedt met green industry stakeholders in Pretoria last week to discuss a weeds risk assessment that has been conducted on 484 aquatic plants, many of which are being sold by mail order internationally, and many of which pose a significant invasion risk to rivers and dams across SA.

It is hoped that risk assessments on all flora and fauna will ultimately provide a scientific basis for issuing or denying permits for the importation of any species into the country.

Mail order trade within the country is also of concern. Last year the Kempton Park Post Office intercepted a shoe box, posted in Polokwane and destined for an address in Bellville, which contained three 1.5-metre Bushveld cobras wrapped in pillow cases.

The message for gardeners and pet lovers is clear: buying plants and pets on the internet can be a danger to the health of your local environment.

Until now, the significant clean-up cost of a plant or pet that jumps the garden fence and invades local ecosystems has been borne by taxpayers.

With the establishment of the polluter-pays principle in the future, people who bring potentially invasive species into the country will be responsible for clean-up costs if those species become garden escapees and invade local ecosystems.

Cape Town is currently home to the country’s most progressive invasive species programmes. Backed by government job creation policies, National Resource Management Programmes (Working for Water, Working for Wetlands, Working on Fire) fund an Early Detection and Rapid Response (EDRR) programme which has been rolled out by the SA African Biodiversity Institute nationally, but implemented by the City of Cape Town Invasive Species Unit locally.

“We currently have three rapid response clearance teams,” says the city’s invasive species manager, Louise Stafford.

“Each team has five or six workers, and we are clearing pampas grass, red valerian and Spanish broom in Hout Bay, Camps Bay and Gordon’s Bay.”

Stafford says that d

etecting and removing invasive species in the city before they become invasive is important.

“With the help of local experts, we have identified 15 target invasive species for control in Cape Town.

“We need gardeners and hikers to join our spotter network (www.capetowninvasives.org.za) and give us the location of any of these 15 target invasive species, even if they are in local gardens. Tell us where they are, and we will come and help you remove them,” she says.

What are the targeted invasive species in the city?

A third of the list is made up of Australian wattles such as the pepper tree wattle (Acacia elata), kangaroo wattle (Acacia paradoxa), hop wattle (Acacia stricta), screw pod wattle (Acacia implexa) and mountain cedar.

Also on the list are species relatively unknown to gardeners, such as the red-flowering tea tree (Melaleuca hypericifilia) and the Australian cheesewood or sweet pittosporum (Pittosporum undulatum). Two other species, the bloodberry (Rivina humilis) and balloon vine (Cardiospermum grandiflorum), are already a huge problem in KwaZulu-Natal, and there is a big concern that the plants have been sighted in Cape Town.

Better known to gardeners will be the red valerian (Centranthus ruber), which is spreading like wildfire into the fynbos biome, as well as the tree of heaven (Ailanthus altissima), pampas grass (Cortaderia selloana), purple loosestrife (Lythrum salicaria), sweet hakea (Hakea drupacea) and Spanish broom (Spartium junceum).

Red valerian is a classic garden plant that has jumped the garden fence, and is aggressively invading the edges of Table Mountain National Park.

With a pretty pink or white flower, red valerian comes from the dry Mediterranean region. Its fleshy taproot acts as a water reservoir, allowing the plant to thrive in our hot dry summers. It flowers from September to April, and each plant produces hundreds of seeds which can invade an entire hillside of fynbos within a season.

While the 15 target plants are the focus of the local rapid response teams, the gardening industry continues to work in partnership with the government to prevent internationally known invaders from being grown and distributed in the country.

In 2003 snake grass, or horsetail (Equisetum hyemale), was identified as a potential ecological invasion threat to SA by local growers looking to import new species.

Although snake grass is used extensively by garden designers in Europe, the SA Nursery Association and SA Landscapers Institute have worked hard to discourage members from growing or distributing the plant locally.

Even the national flower auctions (Multiflora) have tried to make sure that snake grass is no longer sold to local florists.

“The cost to taxpayers to remove snake grass if it were to jump the garden fence and invade Cape river valleys would be enormous,” warns nurseryman Morne Faulhammer, from Superplants Tokai.

* Have you seen any of the 15 targeted invasive species in the city of Cape Town?

Join the Spotter Network at www.capetowninvasives.org.za, or report a sighting to the Early Detection and Rapid Response teams by e-mailing [email protected]

Learn more about invasives at www.capetown.gov.za/edrr. - Weekend Argus