Van Helmont planted a 5-pound baby willow tree in a large pot filled with 200 pounds of soil. For the next five years, he watered it and watched it grow. Then, after those five years had passed and the tree had grown, he took the tree out of the pot and weighed it again: it stood at 169 pounds—164 pounds heavier than it had been at the beginning. But most important, the weight of the soil in the pot remained virtually unchanged. That meant that the 164 pounds of tree had to have come from somewhere else. So how do plants make their… plant stuff, if it isn’t from soil? Back to the tiny sprout
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