The woods are mostly bare and gray, but American beech still shines. The trees, especially the young trees, retain their coppery leaves until spring. Beech is the bright ornament of the dark woods, gold leaf flecking the gloom.
The leaves are exposed to all of winter’s assaults and many of them abrade away until all that is left is translucent paper, etched with veins.
Other trees weather more slowly. Perhaps they grow in slightly more sheltered areas or have a genetic propensity for toughness. Their leaves keep the full, metaled color of autumn.
Botanists are fond of classically derived English neologisms to describe their plants and the scientists have not let us down here. Unfallen leaves are “marcescent” (from the Latin, marcesco, wither).
But nomenclature is easier than explanation. Why might trees be marcescent? One idea is that a fuzz of leaves might protect nutritious buds from browsing animals like deer. Having watched goat lips strip shrubbery, I initially found this explanation unlikely. Browsers are adept at taking what they like and leaving the rest. Goats work around tiny thorns with ease. A few crisped leaves would be unlikely to keep deer away from beech buds. But my skepticism should be tempered by actual experiments. I know of no such experiment in North America, but a study of beech, hornbeam, and oak in Denmark did find that marcescence had a protective effect for beech and hornbeam, but not for oak. Apparently, the lower nutritional content of the leaves compared to buds and twigs acted as a deterrent for deer. The fact that marcescence is most common in young, short trees and on the lower branches of older trees is another piece of evidence in favor of this hypothesis.
On the other hand, retained leaves may act as cues for ovipositing insects in the spring. Or so it appears for gall-forming cynipid wasps infecting one species of California oak. This tree species lives in a very different environment, but galls are also common in Sewanee’s forests.
Another idea is that the retained leaves subtly change the micro-climate around buds. There is experimental evidence for such an effect in Andean plants with rosettes of marcesent leaves. It is possible (although no-one has checked, that I know of) that the ice and snow that gathers on marcescent leaves might act as a buffer, protecting buds from the more extreme winds and temperatures of winter.
I encourage you to seek out beech on your woodland walks. The species is found all over eastern North America. On the southern Cumberland Plateau it has an odd distribution. Puckette, Priestley, Kuers and Hay’s excellent 1996 guide to Sewanee’s trees states that beech is found “almost exclusively in the bottomlands and the neighboring lower slopes of coves.” I’d add that the species also likes (strangely) dry ridges and the streamside habitat of the eroding bluff. It may be that the semi-domesticated hogs that ran through these forests for decades have caused the species to have a more patchy distribution than it otherwise would have done. Beech nuts were favorite food for hogs and in the late 1800s and early 1900s it is likely that almost no young beeches germinated across large parts of the mountain. The species’ present-day distribution is therefore hard to interpret.
Look closely and you’ll see another interesting feature: needle-like buds. Unlike the rotund buds of oak, ash, and maple, beech has stilettos on the ends of its twigs. They are quite remarkably elongate.
I am not the first person to marvel at this species. I have heard that Native Americans in these parts viewed groves of beech as sacred places. One such grove, in Champion Cove, has come up repeatedly in conversations over the years. A destination, perhaps, for a pilgrimage next year.