Twig Anatomy

I have to admit I’m not the best at identifying trees. The ones with compound leaves all look the same to me. Oaks can hybridize and can be a real challenge.

Trees can be identified by other things besides their leaves. Some have distinctive bark, like the corky warts on hackberry trees and flaking bark on sycamores. Not to mention the fruits and seeds they produce too.

Trees can also be identified by their twig. It’s a good way to identify them in winter. This is a twig on the cottonwood tree in my backyard, taken the end of October before the leaves all fell off.

The picture shows the reddish bud of next-year’s leaf and the scar where this year’s leaf dropped from. Buds can have both leaf and flowers, or either one or the other.

Both the buds on this twig are lateral buds. Twigs also have a terminal bud.  The cream-colored corky area below the leaf bud is the leaf scar.  The spots in this area are called bundle scars and are the places where the tree sap entered the leaf. The vertical light areas on the twig are lenticels, and these are patches of loose tissue which let air into the tissue beneath.

This is a bundle scar on our catalpa tree,

and this on our ash tree. Kids would enjoy this scar’s “big grin” and investigating other trees’ twigs too.

6 responses to this post.

  1. Thanks for the lesson, Sensei! 🙂 Nice pictures.


  2. Posted by Therese on November 25, 2012 at 5:17 pm

    Oh Kathy! Love it. Another great lesson! Love the GRIN!!!!!!!!!!!! Keep an eye on your ash tree for those pests that are heading downstate.


  3. Very educational. Wonderful post.


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