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Five Plants That Could Save The World

Tim Entwisle tells us how plants may provide the solutions to pollution and resource shortages

Moringa oleifera improves nutrition in Senegal, image Lauren Seibert, Flickr

Plant products are integral to human civilisation, from staple crops to medicines and commodities, such as cotton, tea and rubber.

Our human civilisation was made possible by a dozen crop plants and a few medicines derived from the plant world. Although around 50,000 plants are eaten or used medicinally around the world, it's estimated that 80 per cent of our calories come from just 12 plants. In fact, 50 per cent come from just three 'grasses': wheat, maize and rice.

Three quarters of prescription drugs in use today were originally sourced from plants and fungi. Perhaps best known are penicillin, from a fungus; aspirin, from a willow; and quinine, from a tropical tree.

Decontamination of polluted land is difficult and expensive, but there are plants that might be able do the job for us.

Then there are commodities like cotton, tea, coffee, rubber and opium. Plants have been pretty important in getting us to where we are today. Whether that's a good or bad thing for the planet is an entirely different matter.

If humans are to survive and thrive on planet Earth and beyond, we'll need to look for new plant-based solutions. Maize, rice and wheat will continue to be important, especially as perennial and more drought/salt tolerant forms are developed — most likely using genes from wild relatives.

Local fruits and vegetables will provide important additions to our diet as well, but which plants will dramatically change our lives for the better? This is my somewhat eclectic list.

1. Water purification plant

In 2010, Canadian researchers showed that the seeds of a small tree, Moringa oleifera, killed enough bacteria in polluted water to make it safe to drink.

A billion people in developing countries use untreated water to drink, prepare food and wash. It is estimated two million people, most of them under the age of five, die each year from diseases contracted from this water.

Moringa oleifera is grown widely in tropical regions of the world and already yields cooking and lighting oil, fertiliser and food. Pretty much all parts of the plant are eaten — leaves, flowers, pods (called 'drumsticks') and seeds.

Now another use has been found. Crushed into a powder and added to water, this plant can reduce bacteria by up to 99.99 per cent and remove cloudiness. Better still, it is easy to propagate and grow, and is highly drought resistant.

A species of prickly pear may also do the same thing. Researchers in South Florida added the slimy insides — mucilage gum, or goo — of this cactus to dirty water to kill bacteria and made it almost drinkable. It turns out this plant was used to purify water by Mexican communities in the 19th century.

2. Heavy metal plant

Many activities of modern life — including mining, industry, intensive agriculture and plastic disposal — result in heavy metal residues. Decontamination of polluted land is difficult and expensive, but there are plants that might be able do the job for us. In 2014 a new species in the violet family from Luzon Island in the Philippines was described.

Rinorea niccolifera is a shrub which grows in nickel-rich soil and has the ability to extract and store nickel. Along with another 450 plant species that 'like' metal, it could be used to restore polluted soil, and the harvested plants could even be mined for metal.

3. Medicine tree

The Neem tree first came to my attention a decade ago, when I read about it in Andy Beattie and Paul Ehrlich's fascinating book, Wildsolutions.
This book is a perfect primer and explains how we can learn from animals and plants to make our human lives easier and better. Beattie and Ehrlich predict Azadirachta indica (the Neem) is destined to become the world's most valuable tree crop.
It isn’t yet, but it is brimming with benefits to humans. Considered to be a divine tree in its home on the Indian subcontinent, almost every part of the plant is used in some way, from treating ailments and discouraging pests, to making soap and feeding stock. Apart from saving human lives, it might one day provide home gardeners with an insecticide that doesn't harm birds and mammals. Just watch out if you live near native bushland in the tropics — it is a little too easy to grow and can become a troublesome weed in northern Australia.

4. Algal rocket fuel

Various species of alga are already used for food (think sushi), as a thickening agent (think toothpaste) and for fertilisers (think Seasol). Algae make it onto this list for their potential as a new biofuel.

Species such as Botryococcus braunii, a microscopic green alga found in freshwater lakes around the world, are relatively easy to grow and harvest, and might even soak up waste carbon dioxide from coal-fired power plants.

In 2010, a twin-prop plane made the first 100 per cent algal fuelled flight at a Berlin air show. Two years ago, Rolls Royce and aerospace company EADS announced they were planning a wind, electricity and algal biofuel-powered plane to be built by 2033 which would produce 75 per cent less carbon dioxide than today's planes.

In terms of providing fuel more generally, algae may be a part of, rather than the entire solution. Europe, for example, needs about 0.4 billion cubic metres of fuel every year for transport. To supply this from algae would require over 9 million hectares of algal farms, an area about the size of Portugal.

Alternatively, you could wrap your own house in algae and, like a gazebo in London, grow the blue-green alga Spirulina to provide shade, oxygen and decoration, and to supplement your diet. An algal-covered building in Germany generates enough biofuel to heat itself and its water supply (although some tenants are annoyed by the 'rhythmic pumping noises').

Oyster Mushroom, Image courtesy Jim Tunney, Wikimedia Commons

5. Oil eating fungi

At the other end of the oil cycle, we need something to mop up oil when it contaminates water and soil. Fungi might provide a solution here. Fungi are not actually plants, in fact they are more closely related to humans than to plants, but they are considered an honorary part of botany and we study them in botanic gardens.

Fungi do lots of good for us already, supporting many of the plants we need to survive, as well as providing a source of antibiotics and food. As a kid I was told to put a shovel full of soil on top of oil spilled on concrete and leave it there for micro-organisms such as fungi to break it down. More recently, the use of fungi has been raised in relation to major oil spills and soils polluted with mercury, dioxins and even radioactive waste (such as in the area around Fukushima).

>The oyster mushroom (Pleurotus) has been mentioned in dispatches as one of these potential saviours after trials in the laboratory. In the rainforests of the Amazon it has also shown potential to clean up the toxic waste pools that remain after oil mining.

This article is reprinted with the kind permission of the ABC, and was first broadcast on Blueprint for Living on RN Saturdays at 9am (see / Radio National / Blueprint for living).


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Tim Entwisle

Currently the Director of the Royal Botanic Gardens, Victoria, Tim was also Director of the Royal Botanic Gardens and Domain Trust in Sydney for 8 years and spent 2 years at Kew Gardens. Tim blogs and tweets to promote his passion for plants. @timentwisle

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