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Oak Leaf Shapes & Sizes

11-15-16-oak-leaves-049a1752There are roughly 90 species of oak trees in North America, several of which can be found in New England. (Eastern White, Northern Red, Eastern Black, Burr, Common Chinkapin, Swamp White, Pin, Chestnut, Bear, Scarlet and Common Post). When identifying oaks, several characteristics, such as buds, bark, branching pattern and leaves, can be used. Most Northeastern species of oak have lobed leaves, with the lobes deep or shallow, pointed or rounded.

One thing all oak leaves have in common is their variability. Even on a single tree, you can find leaves of widely differing shapes. One reason for this is that the amount of sunlight that reaches them affects their shape.   Leaves that are shaded are not only often larger than those that are bathed in sunshine, but their lobes are far more shallow. Both of these traits maximize the intake of sunlight.   Canopies of oaks have a larger proportion of small, deeply-lobed leaves than lower down on the trees, where you can often find relatively large leaves that appear to lack lobes completely. The two pictured leaves come from the same Northern Red Oak.  Can you tell where on the tree they probably grew? (Thanks to Penny March for post idea and leaves.)

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11 responses

  1. Alice Pratt

    Extremely interesting! Thank you! I had no idea there are so many species of oaks.

    November 15, 2016 at 7:37 am

  2. Cindy

    Excellent post! Thank you Mary and Penny. 🙂

    November 15, 2016 at 7:37 am

  3. Bill On The Hill...

    Great post Mary… I love oak trees, all varieties, the ” Ents ” of Middle Earth come to mind when I encounter stately oakes, although tulip trees with their massive diameter trunks reaching for the heavens leave me in awe too… Then there are the chestnuts, beeches, sycamores, etc. Yes, I love all things trees… :>)
    Bill Farr…

    November 15, 2016 at 7:51 am

  4. Mary,

    Fascinating, as always.

    If we ascribe “intelligence” to the oak trees, perhaps the evolutionary type, we could slightly modify what you wrote. “The tree forms deeply-lobed leaves in the canopy since this shape allows more sunlight to filter through to the more shaded leaves below.” So do some lower leaves become larger and have less deep lobes or do some canopy leaves become more deeply lobed or are both at work? What would the leaves on this oak look like if they all got the same amount of sunlight? Your post implies deeply-lobed, but I wonder.


    November 15, 2016 at 7:54 am

  5. Roseanne Saalfield

    Mary, Thank you much. It’s as if you were walking behind me and Jim before sunset at the Oxbow Wildlife Sanctuary in Harvard yesterday. I’ve been reading David Sibley on Oaks and trying mightily to improve my id abilities. I learned about shad leaves and sun leaves and the variations in leaf shapes at different parts of the tree and among smaller trees and grown up trees. And the need to use other clues beyond leaf shape alone to make an id. Sibley says you have to just give up and cry Uncle with some oaks because of their disposition towards hybridization with families. That’s the only piece I’d add to this post if you wanted to expand your oak talk. We often find, in our family, that you are thinking about just what we are just when we are thinking it. Just bought your new book for our 5 year old grandson who loves loves loves animals. It’s time for me to contribute to the blog again.

    November 15, 2016 at 8:50 am

  6. As I was hiking with some friends, we were looking at white oak and red oak leaves. One of my friends was wondering how she was going to remember that the lobes on white oak are rounded and are pointed on the red oak. Suddenly she said, “Oh, I see. White oak has wounded widges (rounded ridges)!”
    Now I smile every time I see an oak leaf and pass on this mnemonic whenever I can!

    November 15, 2016 at 11:52 am

  7. Peter Storrs

    Hi, Mary I sent 3 photos of an ermine which I saw while I was walking this morning. I was not tech savvy enough to put the comment with the photos but hope you are able to see both the photos and my comment. The ermine seemed to be about 12 inches long with about an 8 inch tail. His tail had some black at the tip and also his hind legs seemed to still carry black coloring. He looked at me curiously for about 3 minutes so I was able to snap a few pictures and then he scurried back into his home in an old stone wall. I thought you might enjoy the photos for your blog. Caroline Storrs Cornish, NH

    November 15, 2016 at 12:51 pm

    • Hi Peter, I’m afraid WordPress doesn’t allow photos to come through. Could you send them to me at Very exciting – I’ve never managed to photograph one!

      November 15, 2016 at 3:12 pm

  8. Thank you, Mary, for this post. Very interesting.

    November 15, 2016 at 8:31 pm

  9. I have been planting oaks of different species and hybrids for over 30 years and growing out seedlings of locally growing trees for about 20 years. Young oaks can have leaf shapes that change in time and will finally settle on a shape, which is usually more indented and smaller. You can have a young oak that is growing in the shade with large leaves with less indentation that once it grows tall enough to reach more light will end up with smaller leaves. Bur Oaks (Quercus macrocarpa) that are growing in the Champlain Valley have the most diversity of leaf shape that I have ever seen. I believe that I could collect several leaves from many individuals and you would be able to organize them by shape and size that would identify individual trees.

    November 16, 2016 at 8:29 am

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