Tuesday, May 02, 2006

Dispatches from the fern frontier

Just as Lewis and Clark are celebrated in the United States, so too, in Australia, are Robert O'Hara Burke and William John Wills, leaders of the first European expedition to cross that island continent. In 1860, Burke and Wills, along with two other expedition members, John King and Charles Gray, made the entire journey from Melbourne in the south to the Gulf of Carpentaria on the north coast. On the way back, however, through a combination of bad planning and bad luck, they ran out of food. Gray died, but the others turned to a wild resource that they had learned about from some Aborigines: the sporocarps--the hard, bean-like reproductive bodies of a small fern. The fern, Marsilea drummondii, called nardoo by the Aborigines, is more commonly known elsewhere as water clover because of its four leaflets. In a time of need, here, it seemed, was a fern friend indeed.

Burke and Wills prepared the sporocarps the most sensible way they knew how: they ground them into a powder, added a little water, and molded the mixture into small cakes. These they dried and baked in the hot ashes from their campfire. The food satisfied their hunger, but, mysteriously, they still became weaker with each passing day. In the end, Burke and Wills both died of malnutrition; King was rescued, but he suffered permanent nerve damage in both legs.

For many years, it was assumed that the sporocarps simply lacked food value. But about ten years ago, nutritionists provided a new explanation. The sporocarps, they discovered, are loaded with thiaminase, an enzyme that destroys thiamine, or vitamin [B.sub.1]. When they examined the explorers' journals, they found recorded a classic progression of the symptoms of thiamine deficiency, or the disease known as beriberi.

So much, it would seem, for Aborginal knowledge! But why didn't the Aborigines die from eating the sporocarps of nardoo? The secret lies in the preparation. Unlike Burke and Wills, they mixed the ground-up sporocarps with enough water to make a kind of drink or paste, which they spooned into their mouths with a mussel shell. Diluting the thiaminase, it turns out, decreases its harmful effects to the point that the plant is safe to eat. The mussel shell was also a smart move. If, for example, they had rolled up a eucalyptus leaf to make a spoon (a common Aboriginal technique), the enzyme could have latched onto organic molecules in the leaf that would have increased its potency.

by Robbin C. Moran

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