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(nutation) The circular or elliptical movement of the stem tips of many plants. Due to a shift in the region of most active cell division in the stem, the growing tip swings in a characteristic manner, either clockwise or anticlockwise depending on the species. If during these movements (which seem to be dictated both by internal stimuli and by gravity) contact is made with a solid object, the plant begins to twine around it. The importance of gravity to the response can be demonstrated by inverting a plant that has already entwined a support. The tip and the last two or three coils straighten out and become erect before once again coiling upwards around the support in the characteristic direction.
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