Explorers in the middle of the 19th century relied on stable, portable sources of protein and carbohydrates in the form of dried meat, flour, oatmeal and rice. They also included fruit and vegetables in their diet to ensure they had adequate sources of vitamins B and C, thereby avoiding diseases such as scurvy and beri-beri.
Burke included supplies of lime juice, preserved vegetables, dried apples and other fruits among his provisions. However, when he set out from Cooper's Creek, he seems to have had only a few tins of the preserved vegetables to supplement a diet of dried meat, flour, oatmeal and sugar. By the time they were on their way back to the Creek, the explorers were living on dried horse and camel flesh, and displaying symptoms of vitamin B deficiency - weakness and acute pains in the back and legs.
The explorers were certainly willing to try bush tucker, but their attempts to get it were not always successful. A large snake which they ate gave Burke a violently upset stomach, and a bird which King shot turned out to be 'all feathers and claws'. The fleshy green leaf portulac was another staple and an occasional plump rat was a welcome treat. Once back at Cooper's Creek, they had a brief respite in the supplies left at the camp by Brahe - more flour, sugar and dried meat.
Food from the Aborigines
The explorers also received gifts of fish from the local Aborigines. Burke made one of his worst mistakes by finally refusing these gifts, apparently out of resentment at being expected to offer something in exchange. Another gift from the Aborigines was 'pitcheri', the leaves of Duboisia hopwoodii which, when correctly prepared, are enjoyably narcotic. King compared its effect to 'two pretty stiff nobblers of brandy'.
The Aborigines also gave them nardoo(Marsilea), a fern whose spores can be ground into an edible flour. The Aborigines had learned in thousands of years of trial and error that ground nardoo must be soaked in water before being eaten. The water leaches out an enzyme called thiaminase which destroys thiamine (vitamin B1). The result of ingesting thiaminase is thiamine deficiency, which undoubtedly contributed to the deaths of Burke and Wills.
The scientifically-minded Wills knew that something was wrong. Nardoo seemed to sustain the Aborigines, and it satisfied the pangs of hunger, but he and his companions 'derived no benefit from it'. It passed through their bodies virtually undigested. With remarkable objectivity he observed in his last letter to his father that 'starvation on nardoo was by no means unpleasant'.
Nardoo became the unofficial floral emblem of the failed expedition. A number of specimens were brought back by the relief party, and treasured like holy relics. William Strutt was careful to include a patch of it in his drawing of the death of Burke, and Charles Summers worked it into the floral border on his monument to the explorers.