Originally published in Pulpit Helps, December 2005.
Ever wondered why plants grow upwards instead of sideways? How about why roots grow down instead of up? Plant scientists have discovered part of the answer, and it is a plant hormone. Plant hormones are different from animal hormones, but work in the same way. Auxin is the hormone that controls plant growth, and the way it works is nothing short of miraculous.
Think of a sapling growing on a steep hillside. Many such baby trees bend out at first, but then turn straight up. This happens because more auxin goes to the underside of the branch tip than to its topside. The greater quantity of auxin underneath stimulates extra growth, and this unequal growth forces the branch to bend upward. When the branch tip is straight up, the amount of auxin on either side is equal, and all sides grow at the same rate.
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