All the stems of the morning glory plants growing on my balcony coil in the same direction. When I moved some of the plants, I recoiled them by hand onto the strings they creep around. Those that I had coiled in the 鈥渨rong鈥� direction started to coil in the 鈥渞ight鈥� direction as soon as they could. Why is this?
鈥� Some winding plants such as and wind counter-clockwise (CCW). Others, such as hops and honeysuckle, wind clockwise (CW). Supposedly, you should not force them to wind in the 鈥渨rong鈥� direction or they will wither.
Although it is said that hops wind CW to follow the sun, the actual direction of winding is determined by the plant鈥檚 genes and the pull of gravity.
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鈥淭he direction of hops鈥� winding is determined by the plant鈥檚 genes and the pull of gravity鈥�
A Japanese team at Kobe University led by T. Hashimoto chemically mutated straight-growing vines until some wound CCW, then looked at the molecular structure of the twisty bits. They found that a slight change in the structure of tubulin, a microtubule protein in cells, determined the winding direction ().
Another Japanese team, this time led by Daisuke Kitazawa at Tohoku University, found that gravity-sensing cells are crucial for shoot circumnutation 鈥� the bending and bowing of the tip 鈥� and the winding response ().
So a plant鈥檚 gravity sensors tell it which way is up, and its tubulin structure determines whether it winds CW or CCW in relation to the vertical.
Quinn Smithwick, Cambridge, Massachusetts, US