The landscape is always a surprise to me once the leaves are gone.
I tell people what to expect, I write about what to expect, I remind myself what to expect, but even after all of those words and thoughts, when the leaves drop and the forest opens up with distance views, I am annually amazed.
A lot of my time is spent on the Great Allegheny Passage Trail in the vicinity of Ohiopyle and Confluence. During the late spring a veil of green forms a canopy that threads down to the woodland floor. Prominent parts of the landscape, like the rapids of the Youghiogheny River, are concealed by late May. By Memorial Day the rapids can't be seen from the trail, and the only way I know they exist is by their muffled sound.
By Columbus Day enough leaves have fallen that the rapids reappear deep in the valley through the maze of tree trunks. In late November when the last of the withered leaves are blown from the branches, the world along the trail becomes much bigger.
However, the leaves don't vanish without a trace. The dried brown leaf blades litter the forest floor in deep layers. As moisture and organisms of decay get to work the softer part of the old leaves are broken down into their basic elements and returned to the soil.
Tougher parts of the old leaves remain longer, but are nevertheless acted on by a myriad of agents in the soil and are deconstructed. The whole process is a resource conservation program called recycling. It is a function of natural systems that has been used since life began on earth.
Beyond the obvious, leaves leave other traces.
From a distance, woody plants in winter look pretty much the same as they did in the summer, only without leaves. But, if you get close, real close, there are differences. Working from the trunk, out the larger branches, along smaller and finally the smallest branchlets, or twigs, you will find the traces of last season's leaves.
Most of the trees in this region lose their leaves in the fall and are thus called deciduous. When the growing season comes to an end with shorter days and colder weather, woody plants begin to grow a corky layer between the twig and stem of the leaf. Once this layer grows thick enough, the leaf separates from the twig and the old connections are sealed.
On the smallest of twigs are the former points of attachment of last season's leaves. They are called leaf scars. On some species they are tiny, on others large, depending on the size of the leaf that was attached. Leaf scars come in a variety of shapes including ovals, crescents, hearts and circles. Within the scar is a distinctive pattern of tiny raised dots. These sealed off plumbing connections carried water and food to and from the leaves to the twigs, branches, trunk and roots. The little dots are bundle scars.
Each species of woody plant has a unique pattern and size of leaf and bundle scars. These are as distinctive as the flower, leaf size and shape, bark pattern, or fruit. Because of that distinctiveness, the old traces of the leaves allow us to identify the tree in the winter.
The trick is to first find a twig. Since most are high in the canopy of the tree this can be a real problem. The easiest solution is to look for smaller trees where the top and side branches are easily reached. After windy days or a snow and ice storm, twigs are broken off and fall to the ground where they can easily be examined.
The second trick of identification of woody plants in winter is having a good hand lens to see the sometimes tiny leaf scars and patterns of bundle scars. A 10 power (10x) lens is easy to use for most work but some of the smallest features will require a 20 (20x) lens.
Finally a good identification manual is a must. Several are available, but I still rely on "Woody Plants in Winter," by Earl L. Core and Nelle P. Ammons, Boxwood Press, 1958. I still have a tattered copy from my undergraduate days at WVU. The manual is a classic and is now in its 15th printing by the West Virginia University Press (ISBN 0-937058-52-1).
The accompanying photograph is of the terminal, or end bud, of a common shrub, hobblebush (Viburnum alnifolium). This is an easy shrub to start with since it has such a distinctive heart-shaped leaf scar with three large bundle scars that can be seen on the end of the twig below the bud. The other quality that makes hobblebush easy to identify in winter is the large and distinctive end or terminal bud that looks like a tiny leaf curled in upon itself.
Not all woody plants are going to be as easy to identify as hobblebush. Wild black cherry (Prunus serotina) has slender twigs, tiny buds, minute leaf scars and almost microscopic bundle scars. In this case it's best to look for other distinguishing features of the tree for identification. A combination of slender reddish brown twigs, and a very flaky-rough, dark black bark on older trees, are better identification features than the leaf scars.
Along with the traces that the leaves leave behind, woody plants have other winter clues to their identity. Dried fruits, nuts, and seed pods remain attached to twigs through the winter. Tulip tree (Liriodendron tulipifera) is one of the tallest of our native woody plants and the twigs are almost always inaccessible. However it's easy to recognize a tulip tree in the winter, even from a distance, because of the cone-shaped fruits held erect at the ends of the twigs all winter. In this case, a pair of binoculars is handier than a hand lens.
For the next several months the woods are wide open, free of insects, without the distractions of all those colorful wildflowers, and usually have fewer people. So, it's a good time to get out on your own and do a little winter identification of woody plants.
Paul g. Wiegman is a freelance writer, photographer and naturalist born and raised in western Pennsylvania. Write to him c/o Tribune-Review, 622 Cabin Hill Drive, Greensburg, PA 15601; or e-mail him at pgwphotography@earthlink.net .
