From Seed to Seed:
Plant Science for K-8 Educators

 

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    Response to Physical Contact

Plants respond to touch. This may sound like something out of one of those "new age" gardening guides-"talk nicely to your plants, play soothing music, and stroke them lovingly," etc. The ability to respond to touch seems to belong solely to the animal world.

But consider the tendrils of your pea plants twining around their string supports. Or your morning glories, winding around their trellis. These are examples of plants responding to touch. How else would they know when and where to begin winding?

When a morning glory vine touches a support, the stem cells begin to grow at different rates, causing the stem to bend and curve around the support. This phenomenon is called thigmotropism (Gr. thigma = touch). Again, the mechanism for this is the migration of auxin-but just what happens to stimulate this migration and the resulting difference in growth rates remains a fascinating mystery.







 

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