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

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As a plant biologist, I have been interested for a long time 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 not thrive.

I was therefore intrigued by the plant that 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. It belongs to the family of plants called Aizoaceae, which includes many species that can tolerate hostile environments.

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

It has been described as both an annual plant and a perennial, but this can be influenced by the availability of water and climate. His genre name derives from "four" (tetra) and "angle" (gonia), which refers to its four-corner pod.

The plant has an interesting history, it was collected in Australia and New Zealand by the British botanist Joseph Banks and brought back to England in the late 1700s. It looks like the Endeavor was consumed on their return trip so to ward off scurvy.

Its seeds were then distributed throughout Europe and it seems that it has become a popular summer vegetable in Victorian England and France.

Warrigal's green leaves have a sweet, spinach-like flavor and can replace this vegetable in most recipes. It is becoming increasingly popular with chefs as bush food (although it is now mostly commercial) and is on the menu of many upscale restaurants.

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Research has shown that it is rich in fiber, vitamin C and healthy antioxidants, but also in oxalates. At high concentrations, oxalates can cause an accumulation of calcium oxalate in your body, which can turn into kidney stones.

However, many leafy vegetables, including spinach and kale, have similar high concentrations of oxalates and are eaten raw without fear of deleterious effects. Most recipes recommend blanching the leaves for a few seconds, which is enough to remove the oxalates from the rejected water.

Tetragonia leaves have also been used in herbal remedies to treat gastrointestinal diseases, as an anti-inflammatory, and more recently it has been shown that this drug has an anti-inflammatory effect. obesity in mice fed a high fat diet.

One of the remarkable traits of this plant are the modified hairs that cover the leaves and stems, particularly dense on the underside of the leaves. These are types of trichomes and in this plant they look like small balloons filled with water on the leaf rather than hairs. Because of their strange shape, they are commonly called "epidermal bladder cells" or "saline bladder".

Their presence gives the impression that the leaf shines in the sun. Although most flowering plants have trichomes, only about 50% of all highly salt tolerant plants have these modified balloon-like trichomes. We are just beginning to learn how they work to increase salt tolerance in plants.

These trichomes can act as salt stores, sequestering the toxic salt from the main part of the leaf, allowing plants to continue to perform 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 very salt-tolerant plant (commonly referred to as the ice plant), which also contains these modified trichomes, has shown that cell enlargement is driven by the consecutive doubling of material genetic. As a result, these large cells have extraordinarily large nuclei.

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

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