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The seeds are only sent out on a fine dry day; but they travel well. It was observed in America that certain poppies had been introduced as weeds at a certain place; in fifteen years they were found twenty-five miles farther on, so that they were colonizing the country at the rate of three-fifths of a mile per annum.[132] The seeds themselves are very light and are of some value; they may be eaten like caraway-seed, as comfits, or crushed to supply an oil for lamps, or used as medicine. It is said that the value of the seed raised in France was in one year £170,000. The heads themselves are also valuable (they are worth 35s. per thousand), and even the dried stalks and leaves, for they may be used as fodder.