They Fold Their Leaves

Black locust, young leaves (photo from Wikimedia Commons)

Now that black locusts (Robinia pseudoacacia) are leafing out in Pittsburgh we can watch their leaves do exercises.

According to Wikipedia black locust leaves fold together at night and during wet weather, a trait of the Legume family called nyctinasty. I’ve often seen nyctinasty in clovers but have never noticed it in black locusts because I haven’t been paying attention. This month I plan to take a look.

It will be a good week to get close to black locusts. They’re blooming now with a sweet grape-like scent. See photos and read more about them in last year’s article: The Sweet Smell of Trees.

4 thoughts on “They Fold Their Leaves

  1. Good Morning and Happy Mother’s Day!

    My husband and I are planning a cruise to Alaska and would like recommendations on what types of binoculars are the best for viewing wildlife, birds and marine animals.

    Thank you so much! I enjoy reading this blog and all the comments. There is so much to learn!

  2. Both clover and black locust are legumes (Fabaceae, depending on authority), many of which show nictinasty, as well as mutualism with nitrogen-fixing Rhizobium bacteria.

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