Warrigal greens are tasty, salty, and covered in tiny balloon-like hairs



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Warrigal greens are covered in balloon-like hairs that store salt.
Mason Brock/Wikipedia

Bronwyn Barkla, Southern Cross University

Sign up to Beating Around the Bush, a series that profiles native plants: part gardening column, part dispatches from country, entirely Australian.


As a plant biologist I have spent a long time interested in what makes plants salt tolerant. Some plants can grow and thrive in very salty soils, saltier than the sea, while others (like most of our staple crops) will fail to flourish.

I was therefore intrigued by the plant I saw growing along the sand dunes around Byron Bay, when I moved to this area to work at Southern Cross University in Lismore.




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This plant was Tetragonia tetragonioides, more commonly known as Warrigal greens, New Zealand spinach or Botany Bay greens. It is in the plant family known as the Aizoaceae, which includes many species that can tolerate harsh environments.



The Conversation

Tetragonia is an attractive succulent (think thick leaves). It is a ground trailing plant, with large triangular light green leaves and small yellow flowers. It is found widely throughout the Pacific region from South America to Japan but is thought to be native to New Zealand and Australia, where it grows mainly along the eastern coastline and in estuaries.

It has been described as both an annual and perennial plant, but this may be influenced by the availability of water and the climate. Its genus name derives from “four” (tetra) and “angle” (gonia), which refers to its four-angled seed pod.

The plant has an interesting history, having been collected in Australia and New Zealand by British botanist Joseph Banks and taken back to England in the late 1700s. There is some suggestion that it was eaten on the Endeavour on their homeward bound voyage to ward off scurvy.

Its seeds were then distributed throughout Europe and there are reports it became a popular summer vegetable in Victorian England and France.


Anna Gregory/Flickr, CC BY-NC-SA

The leaves of Warrigal greens have a mild flavour, similar to spinach, and it can substitute for this vegetable in most recipes. It is becoming increasingly popular with chefs as a bush food (although it’s now mostly commercially sourced), and can be found on the menu of many top-end restaurants.




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Research has shown it is high in fibre, vitamin C and healthy antioxidants, but also in oxalates. In high concentrations oxalates can cause calcium oxalate to accumulate in your body, which can develop into kidney stones.

However, many leafy greens including spinach and kale have similar high ranges of oxalates and are eaten raw with no concern about harmful effects. Most recipes recommend blanching the leaves for a few seconds, which is enough to remove the oxalates in the discarded water.

The leaves of Tetragonia have also been used in herbal medicine remedies to treat gastrointestinal diseases, as an anti-inflammatory, and more recently, it was shown to have an anti-obesity effect when fed to mice on a high fat diet.

One of this plant’s remarkable traits are the modified hairs that cover the leaves and stems, particularly dense on the underside of leaves. These are a type of trichome and in this plant look like small water-filled balloons on the leaf rather than hairs. Due to their odd shape, they are commonly known as “epidermal bladder cells” or “salt bladders”.

Close-up of the underside of young leaf.
Bronwyn Barkla, Author provided

Their presence make the leaf look like it is glistening in the sunlight. While most flowering plants have trichomes, only about 50% of all highly salt-tolerant plants have these balloon-like modified trichomes. We are just beginning to learn how they function to increase the plants salt tolerance.

These trichomes can act as salt stores, sequestering the toxic salt away from the main part of the leaf, which allows the plants to continue to carry out photosynthesis and other metabolic processes that would normally be inhibited by the presence of salt. As the plant ages, these cells can grow to store more accumulated salt.

My work with my colleagues on another highly salt tolerant plant (commonly called the ice plant), which also has these modified trichomes, has shown cell enlargement is driven by consecutive doubling of the genetic material. As a result these large cells have extraordinarily large nuclei.

The balloon-like trichomes on Warrigal greens have extraordinarily large nuclei.
Bronwyn Barkla, Author provided

Growing this native species as a food crop could provide more options for landowners in places where the salt levels are already moderate to high, allowing for better use of agricultural land. It thrives in hot weather, few insects consume it, and even slugs and snails do not seem to feed on it due to the salt content.


Sign up to Beating Around the Bush, a series that profiles native plants: part gardening column, part dispatches from country, entirely Australian.. Read previous instalments here.The Conversation

Bronwyn Barkla, Associate Professor of Plant Protein Biochemistry, Southern Cross University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Koalas can learn to live the city life if we give them the trees and safe spaces they need


Edward Narayan, Western Sydney University

Australia is one of the world’s most highly urbanised nations – 90% of Australians live in cities and towns, with development concentrated along the coast. This poses a major threat to native wildlife such as the koala, which can easily fall victim to urban development as our cities grow. Huge infrastructure projects are planned for Australian cities in the coming few years.

The need to house more people – the Australian population is projected to increase to as much as 49.2 million by 2066 – is driving ever more urban development, much of it concentrated in our biggest cities on the east coast. This is bad news for the koala population, unless the species’ needs are considered as part of planning approvals and the creation of urban green spaces. The good news is that koalas can learn to live the “green city life” as long as they are provided with enough suitable gum trees in urban green spaces.




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Indeed, our newly published research, which analysed stress levels in wild koalas according to their habitat, reveals that koalas are the most stressed in rural and rural-urban fringe zones. This appears to be due to factors such as large bushfires, heatwave events, dog attacks, vehicle collision and human-led reduction of prime eucalyptus habitats. Koalas living in urban landscapes are less stressed as long as the city includes suitable green habitats.

If there are suitable trees, koalas can learn to live among us – this one is next to a school in South Australia.
Vince Brophy/Shutterstock

In other words, wild animals including the koala can adapt to co-exist with human populations. Their ability to do so depends on us giving them the space, time and freedom to make that adaptation. This means ensuring they can carry out, without undue pressures, the biological and physiological functions on which their survival depends.

Wildlife species that lack access to suitable green habitats in cities are at higher risk of death and local extinction. Having to move between fragmented patches of habitat increases the risks. Land clearing and habitat destruction for infrastructure projects and other urban development are compounding the major threats to koalas, such as being hit by vehicles or attacked by dogs.




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How does human pressure cause stress in wildlife?

Animals cope with stressful situations in their lives through very basic life-history adjustments and ecological mechanisms. These include changes in physiology and behaviour in response to stresses in their environment.

We can help make the environment more suitable for wildlife species by ensuring their basic needs for food, water and shelter are met. If animals are deprived of any of these necessities, they will show signs of stress.

So by subjecting wildlife to extrinsic stressors such as habitat clearance, climate change and pollution we are making it even more difficult for these animals to manage stress in their daily lives.

Basically any unwanted change to an animal’s environment that prevents it from performing its basic life-history functions, such as foraging and social behaviour, will cause stress.

So what can be done?

The koalas are telling us it’s a major problem when urban design is not green enough. Innovative solutions are needed!

Cities can do much more for wildlife conservation. Creating safe green spaces for wildlife is critical. Not just koalas but other wildlife such as birds, small mammals, reptiles and frogs can benefit immensely from urban green spaces.

Even in suburbs with plenty of green space, problems still arise because urban planning typically designs this space around access for human recreation and not for the wildlife that was living there before the housing development moved in.

Urban planning should always incorporate the planning of green spaces that are safe for wildlife. Providing wildlife crossings is part of the solution. Another important element is educational programs to alert drivers to the need to look out for koalas.




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Measures like this can minimise impacts on wildlife that faces the many challenges of adjusting to city life.The Conversation

Edward Narayan, Senior Lecturer in Animal Science, Western Sydney University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Could Tassie devils help control feral cats on the mainland? Fossils say yes



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The Tasmanian devil once thrived on mainland Australia.
Shutterstock/mastersky

Michael Westaway, Griffith University and Gilbert Price, The University of Queensland

The Tasmanian devil – despite its name – once roamed the mainland of Australia. Returning the devil to the mainland may not only help its threatened status but could help control invasive predators such as feral cats and foxes.

The idea of returning devils to the mainland has been raised before.




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But now we’ve explored the idea from a palaeontological view. We looked at the fossil record of mainland devils, in a paper published online and in print soon in the journal Biological Conservation.

A well preserved devil mandible (lower jaw) recovered from excavations west of Townsville.
Gilbert Price, Author provided

The fossil record helps us better understand how the devils co-existed on mainland Australia with other wildlife. It also helps us see how these iconic animals may possibly interact with small and medium-sized animals if reintroduced to the mainland in the future.

Back in the wild

Ecologists have reintroduced several apex predators to environments where they were once driven to localised extinction. This has helped restore past ecosystems by providing a clearer ecological balance.

One of the best-known examples is the reintroduction of wolves to Yellowstone National Park in the United States, to check the overgrazing and destruction of habitat by elk.

By reintroducing Tasmanian devils into mainland Australia, can we possibly help restore ecological systems that support devils along with small to medium-sized native mammals?

Native and exotic predators

Tasmanian devils and thylacines (Tasmanian tigers) were displaced across the mainland of Australia sometime after the dingo was introduced from southeast Asia at least 3,500 years ago.

But these iconic Australian predators were still able to survive in Tasmania. The island was created 10,000 years ago by rising sea levels, well before the arrival of dingoes on mainland Australia.

Dingoes have now been eradicated across much of mainland Australia, particularly within the seclusion zone of the dingo fence in the southeast of the continent. The 5,400km fence stretches eastwards across South Australia into New South Wales and to southeast Queensland.

Exotic predators such as foxes and cats now thrive across many parts of Australia, and have devastating impacts on small to medium-sized Australian mammals.

But until recently they have not been able to gain a foothold in Tasmania. Many ecologists believe the presence of the devil has prevented these other animals making their destructive mark on the ecology of Tasmania.

Sadly the situation is changing as a result of the deadly devil facial tumour disease, an infectious cancer that has destroyed many populations of Tasmanian devils. Estimates range up to 90% of some population groups now wiped out.

As a result, feral cats are now moving into former devil habitats and hunting native species on Tasmania.

A fossil window to the past

So what does the fossil record tell us about the past life of the Tasmanian devil in mainland Australia?

The Willandra Lakes World Heritage Area, in southeast Australia, provides an extraordinary archaeological and palaeoecological record of Ice Age Australia.

Recovery of fossils and devil coprolites from eroding bettong burrows at the Willandra Lakes World Heritage Area.
Michael Westaway, Author provided

In the past, skeletal remains buried within the landscape were commonly fossilised. Evidence of small animals that dug burrows (such as burrowing bettongs) and the predators that pursued them in their burrows, are exceptionally well preserved.

Our excavations reveal how devils and other small-to-medium sized mammals and reptiles interacted over more than 20,000 years in this area. Even during the peak arid phase, known as the Last Glacial Maximum, it seems that devils and their prey successfully co-existed.

The fossil record (10,000 to 4,000 years ago): This shows the fauna reference condition prior to the arrival of the dingo. (1 Western Quoll, 2 Tasmanian Devil, 3 Thylacine, 4 Bilby, 5 Western Barred Bandicoot, 6 Southern Brown Bandicoot, 7 Burrowing Bettong, 8 Brush Tailed Bettong, 9 Wombat, 10 Nail-Tailed Wallaby, 11 Hare Wallaby, 12 Western and Eastern Grey Kangaroo, 13 Red Kangaroo, 14 Crest Tailed Mulgara, 15 Greater Stick Nest Rat, 16 Hopping Mouse, 17 Fox, 18 Cat, 19 Rabbit)
Toot Toot Design, Author provided
The contemporary record: This shows today’s situation in the Willandra Lakes World Heritage Area. Light grey animals represent those animals that are now locally extinct.
Toot Toot Design, Author provided

The fossil record shows that the range of habitats occupied by devils in the past was far more diverse than today, with populations being found across environments from the central arid core to the northern tropics.

This suggests that devils today should, theoretically, be able to reoccupy a similarly extensive range of habitats.

Former devil range across Australia as revealed by the known fossil record.
Toot Toot Design, Author provided

Better the devil you know

Some ecologists suggest dingoes should be reintroduced into Australian habitats in order to reduce the impact of cats and foxes on native mammals.

One problem is that dingoes also prey on livestock. This is the reason the dingo fence was constructed during the 1880s.

But devils are not active predators of cattle and sheep. So reintroducing a predator that has a much longer evolutionary history with other native mammals in this country would likely receive far less opposition from pastoralists.




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A reintroduction of devils back to the mainland may be a new approach to consider for controlling the relentless, destructive march of exotic predators and restore crucial elements of Australia’s biodiversity.

It still needs to be demonstrated that devils can suppress the activities of cats and foxes on the mainland, as they seem to have done in Tasmania. Experiments with devils in a range of different settings would help to establish this.

A new research approach involving palaeontologists, conservation biologists and policy makers may help us understand how we can restore biodiversity function in Australia.The Conversation

Michael Westaway, Senior Research Fellow, Australian Research Centre for Human Evolution, Griffith University and Gilbert Price, Lecturer in Palaeontology, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.