Wheat said to have been taken from some of the Egyptian mummies, and sown in British soil. It is, however, a delusion to suppose that seed would preserve its vitality for some hundreds of years. No seed will do so, and what is called mummy wheat is a species of corn commonly grown on the southern shores of the Mediterranean.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
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