In winter it is common to use the pattern by which branches and buds are arranged on a deciduous tree as a first, quick clue to the tree’s identity. There are two large groups of trees, those with alternate and opposite patterns, and a third less common pattern, whorled. Trees with alternate arrangement have only a single leaf/bud/branch attached at one location (node) on a branch. Those with opposite arrangement have two leaves/buds/branches attached at a node, opposite one another on either side of the branch. When more than two leaves/buds/branches arise from a node (rare) this is called a whorled arrangement.
At this time of year, when deciduous trees are bare, you can see the arrangement of buds, branches and leaf scars (where leaves have fallen off) clearly. Relatively few trees have opposite branching – Maples, Ashes, Dogwoods, and Horse Chestnuts – while a majority have alternate branching. More characteristics are needed to narrow a tree down to species, but noting its arrangement is an easy and quick way to eliminate certain species.
Striped Maple (Acer pensylvanicum), named after the vertical white streaks on its bark, is often associated with Moose and White-tailed Deer, both of which feed on its bark. In some places it goes by the name “Moosewood” for this very reason. The shape of its leaves give it another common name, “Goosefoot Maple.” In the spring when Striped Maples are nearly in full leaf, bright yellow bell-shaped flowers appear on long, pendulous strings, or racemes. (The flower stalks of the similar Mountain Maple also materialize after the leaves have matured, but these flower clusters are upright, held above the surrounding leaves.)
Striped Maples have the unusual ability to change sexes repeatedly over their lifetime (as does Jack-in-the-Pulpit), a phenomenon called gender diphasy. Among five study populations located in New Jersey, approximately one in four trees exhibited a change in the sex of its flowers between flowering seasons. The flowers of most Striped Maples are predominantly male. If changes occur in the canopy and new conditions seem favorable, a predominantly male tree can become predominantly female (and vice versa, if conditions deteriorate). Size, injury, and carbohydrate reserves are thought to impact the frequency and direction of gender change. Another unusual trait of Striped Maples is that the final sex of a flower is determined within one month of flowering, in contrast to most woody perennials which set buds the previous year.
White ash, Fraxinus americana, is relatively easy to identify in winter, between its stout, opposite branches and buds and the corky ridges that form diamond shapes on its bark. There are several species of ashes, however, and one feature that distinguishes White Ash is the shape of its leaf scars (located beneath leaf buds) on well-developed branches. Each leaf scar (left by a leaf that fell off the tree) is round at the bottom and notched at the top, resembling the letter “C” on its side. (No other ash has c-shaped leaf scars.) It is often concave along the upper edge and the lateral buds are located within the curved portion of the leaf scar.
Striped Maple (Acer pensylvanicum), also known as Moosewood and Moose Maple, can easily be identified summer or winter by its greenish bark bearing vertical white stripes (hence, its common name). Because the bark is so distinctive, one needn’t rely on Striped Maple’s buds for identification purposes, but they are well worth investigating, nonetheless. Their graceful shape, smooth surface (few bud scales) and pinkish-red coloration distinguish them from all others. These buds and young branches that bear them are devoured by rabbits and hares, are frequently eaten by porcupines and beavers, and provide browse for deer and moose.
Bark, silhouettes and buds are the three keys to identifying trees in winter. My preference is buds, as they are so distinctly different from one species to the next. American basswood, or linden (Tilia americana), is a favorite. Its plump, oval, asymmetrical red buds, bearing only one or two bud scales are unmistakable.