Do you grow cucumbers in your garden? If you've ever seen one growing, you've seen the curious coils made by cucumber tendrils as they grasp a support (or grasp your other plants, yanking them to their doom). What's odd about these curls is that they change direction mid-way through the tendril -- the helix reverses. Now why would that happen? This has been a scientific question for quite a while; Charles Darwin called this helical reverse the cucumber's "perversion."
In this short video from NPR's Science Friday, the science of this odd tendril curl is explained. Plus, there's cool time lapse video of various plants growing, courtesy of Roger Hangarter (he runs Plants in Motion). Enjoy, then go out and observe this in your own garden! (And watch out for cucumber spines. Those suckers are nasty.)
For more on this phenomenon, read Harvard Magazine's article A Cucumber Coil Conundrum. If you're just into time lapse of a cucumber tendril coiling, here it is: