As I traveled into the countryside outside of Adelaide, I was amazed to see fields everywhere blanketed by lovely, tall, purple-flowered plants that were identified as weeds called Paterson’s Curse (Echium plantagineum). Also known as Salvation Jane, this relative of borage, introduced from Europe in the mid-1800s, has become widespread in temperate Australia. It blankets millions of acres—about 300 million—and costs Australians vast sums of money each year, in efforts to reclaim farmland and in lost or sickened livestock. Because even though this attractive Mediterranean native is nutrient-dense, it also contains alkaloids that act on the livers of some animals (especially horses and pigs; sheep, goats, and cattle are affected, but not as much). If grazing animals consume much of the weed, many weaken, some die.
Plants grow quickly and develop large taproots that make them drought resistant. They also produce prodigious numbers of seeds, thus multiplying rapidly. In addition to threatening grazing animals, they also crowd out indigenous plants, grasses, or crops.
But not everyone hates this plant. It is cherished by beekeepers, as bees love it. Which is why there was an ongoing battle for many years about the use of herbicides. Now, attempts are being made to control the weed with non-toxic methods. Because the plant is kept in check on its home turf by insect predators, scientific organizations tested the practicality of introducing insects that would feed on the plants. (A similar approach helped Queensland control a stunning plague of prickly pear cactus—the Cactoblastis moth was introduced and helped reclaim millions of acres of land that had been lost to the introduced cactus.)
Because the flowers of this plant are lovely, people who don’t know what it is think it’s a nice decorative plant. As a result, it has found its way into other ecosystems. Oregon is now fighting infestations of this broadleaf weed. Which is just another example of why, when those nice people at the airport ask you if you have any plant material in your luggage, you should tell the truth—or, better yet, don’t have any. The ecology you might be destroying could be your own. (Most seeds for this particular weed are, in fact, transported in dried plants, so don’t think it’s safe just because it looks dead.)
And here you thought it was just rabbits that became a problem in Australia.