Tree Identification in Winter - Bruce Robinson

Bruce Robinson, Inc., 1894 Camp Street Extension, Jamestown, NY  14701.   (716) 665 - 5477


Introduction

For more than six months of each year most of our area trees are verdantly challenged. This may present a problem for those of us itching to rev up our chainsaws to be in the forest "when the mosquitoes ain't". Although we know much about favoring certain tree species to accomplish various management objectives, identifying them in winter may be frustrating. During this hour we will explore winter tree characteristics unique enough to learn trees by name. Hey - with a little practice you will discover no reason why you can't work in your woodlot every day of the year.

Looking at trees systematically, allows lumping trees into ever decreasing groups until, through a process of elimination, we finally end up reasonably sure of what the tree is not.

For best results, always look at more than one characteristic and examine more than one area of the tree. Ask yourself, "Is the sample I am examining typical of the tree before me?"

Steps to Identification

Step one; determine if the buds are situated on the branch opposite one another or alternating from one side to another. Most trees have an alternating habit . This knowledge helps us little if the sample is alternate but considerably if an opposite bud location is observed. Common to the northeast, Maples, Ashes, Dogwoods, CAPrifoliaceae and HORSE chestnut show opposite buds. Remember MAD CAP HORSE. "Cap" represents the honeysuckle family.

Examine twigs closely. Be sure when comparing characteristics only one growth year is considered. As each bud begins to elongate, scales are shed. These bud-scale scars surround the twig. A vigorous ash twig may show several inches between these bud-scale scars. On the same tree, a slow growing branch may show-bud scale scars so close together as to be indistinguishable.

Examine the end bud. If the bud is a true terminal but, growth stopped during the previous growing season with its development. By contrast, a false terminal bud results when species continues to elongate branches until weather and light conditions force death upon the branch and buds not fully developed. Die back occurs to the first fully developed bud. By late winter most species shed the dead twig portion and the pseudo end bud appears to be a terminal bud. Close examination with a hand lens will show a twig scar with concentric circles of pith, wood, and bark. It will appear that two leaves fell from this juncture. The true leaf scar, however, will not show the concentric circles

Next. examine other scars closely with a hand lens. Stipules, which are leaf-like appendages usually present only during the bud elongation period, leave scars when they fall away. Although most are inconspicuous, sycamores and magnolias (tulip tree is a member) have stipules which completely surround the twig.

Examine twig for spines and thorns. They are not the same. A thorn is a modified branch and a spine is a modified stipule. The spines occur at the location of lateral buds in pairs (black locust, prickly ash). Thorns in cross-section show concentric circles of pith, wood and bark and occur singly (honey locust, hawthorn and several fruit trees).

Close examination of an inner twig exposed by a longitudinal cut reveals pith characteristics. Pith showing uniform density helps little. Hickories, however, show a cavity or chamber at each node or leaf scar location. Butternuts, walnuts and hackberry show chambers between nodes. Pith in cross -section is round and solid for most species. Oaks and poplars have a 5-sided star-shaped pith. Alders exhibit triangular pith.

Use the buds

Buds may provide the most help and will verify an identification based on other clues.

Are buds covered with scales or are they naked (appearing as tiny folded leaves)? Witch hazel and several viburnums have naked buds. Scales on terminal buds of some species may be very large. Shagbark hickory has large scales peeling away from the bud. By late winter some of these scales may be shed. Again, be sure to examine several samples.

Buds of the tulip tree are large with two scales completely covering the developing leaves within the bud. They appear almost glove like.

Quaking aspen is distinguished from big-tooth aspen by buds alone. The shiny, smooth, sharp pointed bud of the quaking aspen has a tip pointing away from the twig. By contrast, each bud scale of the big-toothed aspen is edged with fuzzy almost woolly extensions. The fat bud clings to the twig. In early June the big toothed aspen can be identified at considerable distance as the smoky gray leaves evolve from the woolly gray buds.

Finally, winter tree ID is enhanced by examination of trunks. Always remember most trees change bark characteristics as they mature (the smooth, heavily lenticled bark of young black cherry becomes almost potato chip-like as it matures. Look up into the tree to witness young characteristics. Look closely at ridges and valleys of bark on the trunk of mature trees which break up uniformly. White ash has fairly longitudinal ridges about the same size as the valleys. Basswood, by contrast, will exhibit broad, flat ridges with valleys less than half the ridge width. Both are typically vertical. Although at a glance butternut may appear similar the very wide ridges often cross irregularly.

Does the bark flake easily? Mature hop hornbeam shreds easily from the trunk. A shagbark hickory, although peeling in vertical strips in the same manner forms strong, broad strips of bark. Sycamore bark peels away in large patches with no particular orientation. Birches, especially yellow and paper, peel horizontally in several layered sheets.

As we continue to study tree ID in winter we will learn of new tricks - the wintergreen flavor of the yellow birch twig or the bi-colored green and brown of the sassafras twig but always know that tree ID is not just knowing tricks. Trees are amazing systems and each of the characteristics which help us identify the species in some special way helps the tree to survive.

Summary

I hope your appreciation of trees has been boosted enough to inspire you to ever-greater examination. Perhaps another time we should examine trees in a way almost as overlooked as trees in winter; the underground tree anatomy. Thank you.

References:

Know Your Trees. 1996. J. A. Cope and F.E. Winch. Cornell Cooperative Extension 4-H Bulletin #85. $3.00 postpaid. Cornell Media Services, Resource Center MW, 7 Business and Technology Park, Ithaca, NY 14850

Forest Trees of the Northeast. 1996. J. P. Lassoie, V. A. Luzadis, and D. W. Grover. $17.95 postpaid. Cornell Cooperative Extension. Cornell Media Services, Resource Center MW, 7 Business and Technology Park, Ithaca, NY 14850

 

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