One of my favorite winter botanical activities both at home and when out and about is silhouetting (i.e., studying and enjoying the naked or bareboned look of deciduous trees against a background of various and ever-changing sky, landscape and light conditions). The silhouettes are like a general fingerprint or complex SKU barcoding unique for each species. The primary characteristics one uses to differentiate trees when silhouetting are size, color, form/architecture (incl. overall shape/outline, branch thickness, relative branch orientation and curvature). Also, trunk (bole) shape and proportion, habitat (and associated plants) and occasionally persistent fruit or leaves. Another aspect that becomes more obvious when the leaves are missing is malformation (e.g., galls and brooms, both can sometimes help with ID). Additional facets, not related to ID, include damage, animals and their nests, as well as resident vines which are often potentially harmful to the host. One can also discern whether or not the tree was grown in the open, then low branched, or in a forest (closed) setting. Occasionally several specimens develop in concert to form a unified or singular canopy.
Many tree species are actually easy to identify when leafless, even from afar. One can actually see more with less. In fact, numerous tree species are easier to identify from a vehicle traveling at high speed in winter. The magnificent mottled white bark of sycamore is even more outstanding when naked. And winter's bleak landscape actually accentuates evergreen species, especially conifers -- of which the Midwest has few natives. Among my favorite silhouettes are the old specimens of white oaks (sensu lato). Their grand stature, darkness and captivating fractal form are awe inspiring in the largely colorless winter landscape. The prevalence of old oaks in the Chicago area makes travel for me there in winter tolerable. FYI: I find most red oaks (esp. the pins) coarse and unappealing. I never recommend them.
So, do you know the centered species in the above picture? Any Midwest plantsman worth his or her salt should. It is young sassafras (S. albidum). How can one tell? First, it is a clonal species often associated with the edge of woodlands and fence rows -- notice the line of multiple twisting trunks. The clonal nature makes successful transplanting from the wild difficult. Notice also that the terminal portion of the ascending branches are turned upward like your fingers relaxed with the palm facing up. Moreover, the bark on new growth stems are green -- a characteristic shared with few other midwestern trees other than boxelder. The bark transitions to a relatively smooth silver in the older portions of the stems. If you should ever be fortunate enough to see a really old sassafras specimen you will observe that the trunk often has a distinctive pronounced taper and seems disproportionately big (like catalpa), is seldom tall (perhaps 50 feet) unless it developed within a forest, and the heavily ridged bark will be dark reddish brown with orange undertones. One thousand-year-old specimens have been recorded. I will forever remember the amazing, though declining, aged grove across the road from the now defunct T.A. Foley Hardwood Lumber Co. in Paris IL, as well as the magnificent mixed stand a short distance north of route 36 just east of Tuscola, also Illinois. These groves and the individual ancient specimens had a primeval appearance. I would love to be able to use the present tense verb in the description, but it has been several decades since I last visited and am not certain these natural marvels still exist. If they do, and you are interested in trees, it would be well worth the trip, naked or not. NOTE: the tree, not you.
PS: A Tuscola police department officer has informed me that their old grove is extant.