Bianca de Loryn
College of Arts, Society and Education
17 May 2022
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The wild history of weeds in Australia
JCU PhD student Janine Evans researched the wild history of weeds in Australia for her Bachelor of Arts (Honours) thesis. Janine’s research in the field of environmental history shares the story of how a pretty garden plant, lantana, became a destructive weed of national significance that may never be eradicated.
Lantana camara, commonly known as lantana, is an attractive plant. It is a shrub that typically grows to around two metres tall, with multi-coloured flowers that are arranged in clusters around their stems. But lantana is also an invasive weed.
Janine has dedicated her Bachelor of Arts (Honours) thesis to the history of lantana in Australia, starting from its colonial origins in South Australia in the early nineteenth century. In tow with European settlers, the tropical shrub native to the Americas has colonised the Australian east coast from the Torres Strait down to the Victorian border, as well as many other tropical and sub-tropical regions around the world .
Lantana conquering the rainforest fringes
“Lantana has evolved to be successful, as typical weeds do,” says Janine. “Alfred Crosby, probably the most famous environmental historian, describes weeds as the ‘Red Cross’ — or the paramedics — of the plant world. When the environment gets disturbed or damaged, the weeds rush in and try to repair it.” Especially in North Queensland, lantana has been very successful around the fringes of the rainforest, because the region has a similar climate as the plant’s home in tropical South America.
“The problem with lantana in the Tropics is that it's affecting our biodiversity. Australia has quite a unique environment,” Janine says, adding that the Australian Government has classified lantana as a ‘destructive weed of national significance’. “As the rainforest trees fall, lantana goes in, and it smothers out young saplings, preventing them from establishing properly.”
Lantana - dangerous or useful?
In the mid-nineteenth century, Queenslanders were already observing that the plant was dangerous. Cattle, sheep and goats would eat the poisonous plant and then die if not treated. But not all farmers were wary of lantana. “Some of the farmers in Queensland found the plant useful, especially in the banana growing regions,” says Janine, “not only as a fertiliser, because it contains potash, but also because it keeps other weeds down.”
This was why some farmers actually introduced and encouraged the plant to grow on their property. “They thought they were better off dealing with one type of weed rather than with many, as lantana is effective at killing other plants around it,” Janine says.
What is a weed after all?
Looking from today’s perspective, in a country with some of the strictest biosecurity laws in the world, it seems surprising that people would introduce such a dangerous weed in the first place. The biggest issue was that back in the nineteenth century, there was no legal definition of a weed, yet. In addition, the European settlers thought that almost everything that was coming into Australia from overseas was superior, including plants and animals.
It all started some time around 1841. That is the date of the earliest record that Janine discovered. “I found an article in the South Australian Journal , by a nursery man called John Bailey who came from London,” Janine says. “Then I found another reference to lantana in Camden, Sydney, by John MacArthur. MacArthur was the largest sheep farmer in Australia at the time and he grew the plant in his nursery in Camden.”
‘Improving’ the Australian landscape
Apart from commercial nurseries bringing plants into Australia to make a profit, or other people’s efforts to ‘improve’ the landscape, says Janine, “European settlers also exchanged plants like lantana because they liked the flowers. But once lantana had become established in Queensland’s tropical environment, it simply exploded.”
Even if farmers complained about the weed in the early years of its arrival, the colonial government was slow to act and there was little money available to support its eradication. “The government’s priority was getting the economy going. In Queensland we didn't have gold or other mineral discoveries at the time. That only came later,” Janine says. “The priority around the mid-nineteenth century was on sheep, cattle and agriculture, such as producing exotic fruits.”
Disunity among Queensland’s farmers
Janine adds that Queensland is very decentralised, with the main seat of government in Brisbane while North Queensland towns a long journey away. “They had these divisional boards which oversaw local government areas. You could have one divisional board saying lantana is a massive problem,” Janine says, “and then a neighbouring divisional board might not think it’s such a big issue, as there could have been some benefits for the local farmers.”
A lack of cooperation across Queensland helped lantana to spread. “You can’t control it if everybody is not doing the same thing,” Janine says. “The politicians in Brisbane also argued over how to define a weed for two years.”
Lantana – out of control
Lantana has been targeted for biological control since 1914. By that time, lantana had spread around the entire east coast of Australia making it difficult, if not impossible, to eradicate the weed by one single means. “Carried by birds and floodwaters, the plants are very productive. They produce 12,000 seeds from one single plant," Janine says.
Since the 1910s, several weed killing substances having been introduced and experimented with. So far none have been successful due to lantana being so widespread. "You might be able to control lantana in some places, but other places might be more difficult,” Janine says. “For example, governments can’t control what people do on their private lands. If someone has a plot somewhere with lantana on it and it’s just left to grow, well, then there’s not much you can do about that.”
Lantana and cane toads
When asked if lantana can be compared to cane toads that have also overrun Australia, Janine says, “we can’t really compare animals and plants. Plants move via birds and waterways. But a plant like lantana needs humans to spread it. Weeds like lantana follow human settlement.”
Janine says animals, on the other hand, are very different. “Animals are mobile. They can go where people don’t go. I’m pretty sure cane toads also exist where humans don’t.”
The future lies in the past
After successfully graduating from JCU with a Bachelor of Arts with First Class Honours in 2021, Janine is now taking her environmental history research in a different direction. She started her PhD at the beginning of February.
“I am looking into the life and work of the botanical illustrator Vera Scarth-Johnson. She moved to Cooktown in 1972 and lived there for over 20 years,” Janine says. “Vera wanted to paint all the specimens that were collected by botanists Banks and Solander when they visited Cooktown while their ship Endeavour was being repaired in 1770.”
What was special about the artist was that she worked together with the local Guugu-Yimithirr people. “Vera had a great relationship with them, and they were able to identify the plants in language for her as well,” Janine says.“We've got the benefit of that interaction because we know what the Indigenous names for the plants are now.” Janine’s PhD thesis will also explore how these connections help us to understand how the region’s natural environment was understood and shaped by historical processes.
The outcomes of this collaboration — 140 botanical illustrations — can be seen at the Vera Scarth-Johnson Gallery in Cooktown. To read the outcomes of Janine Evan’s PhD, however, we will still have to be a little more patient.