Our history has centred on the relationship between people and prickly pear, and on the tension between the plant's value and danger. We have also explored the plasticity of plants. Running wild, on the one hand, or domestication and breeding, on the other, can change a species’ characteristics, impact and the attitudes towards it. The history of prickly pear in South Africa shows that categories of alien, bio-invader, weed, useful plant and crop are rather fluid. Much has been written on the blight – both environmental and economic – that bio-invaders can bring. There are certainly many such cases and the South African research is particularly rich in this field. Yet we have, in part, an inverse case. Part of the story consists in successful bio-suppression. Opuntia extirpation campaigns in South Africa have again altered ecological balances in different parts of the country.

We have argued that wild prickly pear has been, and remains, of some significance to poor rural communities in the Eastern Cape. It is still part of everyday life and has left a cultural legacy for whites as well as blacks. By chance rather than intention, the biological campaign, while it greatly diminished prickly pear, did not entirely eradicate it. The fruit can be found in some quantity. However, some opuntia species can still be invasive, compete with indigenous plant species, hurt livestock and also some wildlife. All wild cactus species remain declared weeds and the state is still formally committed to their destruction. Strictly speaking, it is illegal to spread or deal in prickly pear in South Africa.

Is there a route out of this dilemma? Ideally, spineless cactus and prickly pear should be grown as horticultural crops in gardens and agricultural plots, and cleared from all other areas. In this way, those who wish to use the plants – or market their products – could do so, at the same time as natural biodiversity is protected. The government has moved some way down this route by removing spineless cactus cultivars from the list of weeds. At present, however, this scenario is unlikely to be achieved. Many poor people do not have the land on which to grow opuntia or the labour to manage it. Even if they could grow spineless cactus, they would face the task of protecting it against livestock.