By Antony Funnell
![The phloem sap of Phyllantus balgooyi. The green color is due to the high nickel concentration in the sap.](https://canadiancor.com/wp-content/uploads/2022/06/Phyllantus_balgooyi_phloem_sap-274x300.jpg)
When scientist Alan Baker made a cut in the side of an exotic plant in the Philippines jungle, the sap that bled out had a jade-green glow.
The shrub was a newly discovered species, soon to be known as Phyllanthus Balgooyi, one of a rare variety of plants that naturally suck high amounts of metallic elements from the soil.
The fluorescent sap turned out to be nine per cent nickel.
It was a welcome finding, but not a surprise, as Professor Baker’s research into so-called “hyperaccumulators” had already uncovered species that seemed to thrive on everything from cobalt to zinc, and even gold.
“These are plants which can take up elements from the soil [at rates] orders of magnitude higher than normal plants,” Professor Baker says.
Scientists are now on a quest to discover whether farming these plants could provide an alternative to environmentally-destructive mining, while also helping to rehabilitate former mine sites.
Commercial potential
University of Queensland plant specialist, Dr Antony van der Ent calls it “agromining”, but it’s also known by the term “phytomining”.
In his chemical analysis laboratory in suburban Brisbane he’s currently doing tests on perhaps the most well-known hyperaccumulator of them all – the Macadamia tree.
Its leaves and sap, but not the nut, are rich in manganese.
In recent years he’s traversed the globe searching for new species of hyperaccumulators, but COVID-19 has temporarily put that research on hold.
He says the plants are most common in countries around the equator.
“We have found them in Southeast Asia, as well as New Caledonia, and in Cuba and Brazil,” Dr van der Ent says.
He estimates that of the 300,000 known plant species on Earth only around 700 have hyperaccumulating properties.
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