Illinois Natural History Survey - University of Illinois

Make an Oak Tree Collection


Carolyn Nixon


To learn how to identify the oaks in your area, you can make an oak collection.  No, you won’t be collecting trees; just parts of trees!  By making a collection of leaves, acorns, winter buds, and bark rubbings, you will have much of the information you need to identify the tree.  You can make this collection from oak trees on school grounds or nearby parks and natural areas.  Before you collect anything from the trees, make sure you get permission from the landowner or property manager.  Collecting leaves and acorns and taking bark rubbings will not harm trees.  The leaves and acorns of an oak tree will be shed in the fall, anyway.  Collecting twigs with buds should be done with care.  Do not take too many buds from one tree as these are the next year’s leaves.


Leaf Collection:  Use a letter-sized spiral notebook for your leaf collection.  Making a leaf collection can be done any time that the leaves are on the trees. However, it is best to wait until the leaves have reached their full size in late spring or when the leaves are shed in the fall.  Once you have found a tree from which you want to collect, rccord some information about the tree.  Include the date, where ther tree is located, and a general description of the tree.  A quick sketch of the shape of the tree can be useful (see the illustration).  Give the tree a number on you notebook page.  Anything else you collect from this tree will be given the same number.  Carefully pull the leaf from the twig by pushing against the base of leaf petiole (the leaf stem) next to the twig.  By doing this, you should retain the wide, flared end of the petiole.  This may be helpful in leaf identification.  Flatten the leaf against the notebook page and close the notebook.  Turn four or five pages before you collect a leave from another tree.  Once you have collected all the leaves you need, place the notebook on a flat surface and place a heavy book on top of it.  Let it sit undisturbed for at least two weeks.  This will allow the leaves to dry, and they will then remain flat.  After they are dry, you may tape the leaves down to the page.  


Acorn Collection: To make an acorn collection you will need several small paper bags and some 3" by 5" index cards.  Pull the acorn from the tree, or pick one up from the ground directly below the tree.  Make sure the acorn cap is attached.  Place the acorn into a bag.  Write the number on the index card.  Remember, this is the same mumber you used for the leaf collection.  If no leaf was collected, include the information about the tree as well (date, location, description, and sketch).  Acorns from different trees should go into separate bags.  The acorn collection can easily be stored in egg cartons or divided boxes.  Be sure to include the tree number for each acorn on a label that is placed in the compartment with the acorn.  If only a few acorns are collected, the egg cartons are easily cut in half.


Bark Rubbings:  Hold a piece of unlined paper against the trunk of the tree.  Vigorously rub over the paper with a crayon.  This should give you a reasonable picture of the bark.  Make sure you write the tree number on the piece of paper and record the other information (date, location, etc.).


Bud Collection:  Once the leaves have fallen from the oak trees in the fall, and before the leaves begin to come out in the spring, you can collect a twig with its buds.  Cut a short piece of twig from the end of a branch (3 or 4 inches should be adequate).  Tape the twig down to a notebook page and number the twig.  If you know it was the same tree from which leaves or acorns were collected, use the same number that was used for the tree.  Record the date, location, and description of the tree on the notebook page next to the twig.  Use a new page for each tree. 


Once you have your oak collection, use a field guide and try to identify each tree from your collected leaves, acorns and twigs, and your bark rubbings.  Do not get discouraged if you cannot determine the species of oak you have found.  Oaks can be difficult to identify.  Sometimes oaks are hybrids (crosses of two different tree species).  Also, if leaves are collected around homes or parks, the trees may have been planted by people.  Some of these trees may not be native to the area.  Oaks occur over much of the Northern Hemisphere, and many European oaks are widely planted in North America.  Some plant nurseries are even crossing European and North American oaks to produce new types of trees.


Mohlenbrock, Robert H. 1980. Forest Trees of Illinois. Eight edition. Illinois Department of Natural Resources, Division of Forestry, Springfield.  331 pp.


Mille, Howard and Samuel Lamb. 2003. Oaks of North America. Naturegraph Publishers Inc, Happy Camp, California.  327 pp.



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Petiole.pngInclude the enlarged end of the leaf stem.



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