Nardoo or Marsilea drummondii

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Nardoo has a place in Australian history because it’s what Burke & Wills were eating when they starved to death on Cooper Creek. What is it and what does it look like?

Marsilea drummondii or Nardoo is a common and widespread fern found in wetland areas across inland Australia. There are approximately 65 species of Marsilea worldwide and about 6 species in Australia. Marsilea drummondii is a native of inland areas of Australia, occurring in all states and territories except Tasmania and the ACT. It is not tolerant of salt.

Marsilea grows in shallow, still or slowly flowing water such as on the margins of waterholes, claypans, swamps, rivers and their floodplains, and roadside table-drains. It is also commonly found in drying mud where it will persist while moisture is available. But despite relying on water to complete its life cycle Marsilea drummondii is well adapted to arid and semi-arid environments.

It grows from a creeping rhizome (an underground stem), and can form dense, massive 'fields' of nardoo that cover the floodplains following flooding.

The slightly furry fronds or leaves stand erect when growing in mud, or float when growing in water. Each frond consists of two pairs of leaflets arranged in a four-leaf-clover pattern. Flexible stems allow the plants to adapt to changes in water level, while allowing the leaves to float on the water surface so they can have access to light. Being a fern, nardoo has no flowers or seeds, instead reproducing by means of spores contained inside a sporocarp, a hard capsule up to about one centimetre long which grows from the rhizome.

As the mud in which the plants are growing slowly dries out the leaves shrivel and the sporocarps become detached and dry, some lodging in the cracks of the drying mud where they can remain viable for 20-50 years. When enough water is again present, the sporocarps open and new plants are eventually produced (But only after some complicated intermediate stages in the ferns life cycle).

Nardoo plays an important part in the diet of aboriginal people in the semi-arid and arid parts of Australia. After gathering the sporocarps, Aboriginal people roasted the them, before grinding them up & mixing them with water to form an edible dough which was then eaten. In some areas Nardoo was a such an important food that it was processed in large amounts with so-called 'Nardoo Mills' — sets of flat grinding stones found scattered around the edges of water courses such as the Willandra Lakes.

Nardoo is nutritious, but it is also a potentially dangerous source of food, as it must be prepared correctly if it is to be eaten safely. Burke and Wills on their way north through the interior of Australia in 1860-1861, were fed Nardoo that had been correctly prepared by the aboriginal people. However on their return journey, the exploration party prepared the Nardoo plant without help from the aborigines. They neglected to heat the sporocarps first, leaving an enzyme called thiaminase remaining in the ground up food.

Thiaminase breaks down thiamine (Vitamin B1), and prevents it from being absorbed by the body. Thiamine, although needed in only tiny amounts, is essential for energy metabolism, nerve and brain function. A shortage of thiamine results in a condition known as beriberi which can have devastating effects on the nervous, muscular, cardiovascular and digestive systems.

So despite eating up to "four or five pounds a day between us", as Wills noted in his journal, the explorers grew weaker and thinner and developed symptoms such as shaking legs and a slow pulse. On Wednesday, June 12, 1861 Wills wrote... "King out collecting nardoo. Mr Bourke and I at home, pounding and cleaning. I still feel myself, if anything, weaker in the legs, although the nardoo appears to be more thoroughly digested."

Wills couldn't understand why he seemed to be starving, despite eating so much nardoo. He didn’t know about the enzyme thiaminase and how it was destroyed by heat. So although they had enough nutritious food, they eventually died of starvation.

Spare a thought for Bourke and Wills (and King) when next you see some Marsilea. Short of going out into desert areas, you can probably find some in your local nursery as it is now widely cultivated as a garden pond plant.

Nardoo is regarded by some graziers as a useful forage plant but it is probably very low grade fodder and is generally not favoured by stock when alternative feed is available. Sometimes sheep feeding on Nardoo show symptoms of thiamine deficiency. Strangely, although it is often fatal to mammals, nardoo is an important flood-time food for waterfowl.