Many alien plants that have become such a nuisance that they have to be actively eradicated in places are pretty. Doubtless it is their attractiveness that encouraged people to import them for their gardens in the first place. Yet, most of our common garden flowers have originated from elsewhere and no-one turns a hair, so what makes an ‘alien’ an ‘alien’ that becomes known as a ‘noxious weed’ or an ‘alien invasive’? When the rate at which they spread, the harm they do to natural vegetation, and the potential risk they hold for animals and humans become a problem.
Common lantana (Lantana camara) is one such pretty alien.
It originated in tropical America and has spread alarmingly all over the world. In South Africa, both the Eastern Cape and Kwa-Zulu Natal are particularly affected by the infestation of these plants which were originally imported as an ornamental garden shrub. There is no denying the beauty of their multi-coloured yellow-orange flowers.
Birds eat the fruits and in this way the plants have moved from gardens to the veld. Therein lies the problem: this plant is one of the most common causes of livestock poisoning in this country and is thus classified as a Category 1b invasive alien species in the South African National Environmental Management Biodiversity Act of 2004. This means that they have to be removed and destroyed as part of an invasive species control programme.
Common lantana spreads and grows so rapidly that it out-competes indigenous plants by forming dense thickets. These reduce natural pasturage – which obviously affects the amount of grazing available, access to water supplies and severely reduces biodiversity.
Henderson Mayda and Anderson Johan G. Common Weeds in South Africa. Department of Agricultural Technical Services 1966.
Van Wyk Ben-Erik, van Heerden Fanie and van Oudtshoorn Bosch. Poisonous Plants of South Africa. Briza Publications 2005.