Betula populifolia has many distinctive characteristics. Its bark is a pale white but, unlike paper birch, it does not peel. The leaves have a slightly triangular shape to them in contrast to most other common birch species, whose leaves are more oval. This species will grow as a single or multi-stemmed tree depending on site conditions. Gray birch is commonly seen along roadsides, trails edges, and is one of the first woody species to colonize old fields.
Gray Birch: A Great Choice for New England Landscapes
Looking for a great garden tree? Consider the underutilized gray birch (Betula populifolia), a smaller, more drought tolerant alternative to the river birch (Betula nigra) cultivars that have become ubiquitous. Like other native birches, gray birch is an early succession pioneer, one of the first trees to grow in cleared or otherwise disturbed sites. Native to the colder climates of the East Coast, it ranges from Nova Scotia south to Pennsylvania and New Jersey.
Attributes that enable gray birch to succeed as an early colonizer also make it an attractive candidate for home landscapes. It is highly adaptable— easy to transplant, quick growing, and able to establish in dry, poor soils. It needs a fairly sunny location but otherwise is a good tree to try in difficult sites. Gray birch is small and narrow in shape averaging about 30 feet tall and 15 feet wide. With a columnar, often multi-stemmed habit, it can be used as a specimen tree, and also works well planted in a small grove. Its open canopy casts a light, dappled shade. Glossy green foliage turns a showy golden yellow in fall. Attached to branches by longish stalks, its leaves flutter in even a slight breeze. Both the Highline in NYC and the Monk’s Garden at the Isabella Stewart Gardner Museum include gray birch in their designs.
Birch trees are widely admired for their striking bark and gray birch is no exception. Its trunks are a chalky grayish white. Textured horizontally by fissures, its bark is marked all over by irregular black patches where branches once attached. While gray birch can easily be confused with paper birch by the untrained eye, there are several characteristics that distinguish the two. One key difference is that gray birch bark doesn’t peel; this signature feature of paper bark is almost always noticeable, even on young trees. In addition, gray birch leaves have a triangular shape to them, narrowing to a point more sharply than the largely oval paper birch leaves. Their native ranges are also somewhat different. Betula papyrifera needs cool summers to thrive and is much more abundant in northern New England. Further south look for it in shady, moist settings and at higher altitudes. In contrast, gray birch is a common sight along roadsides, woodland edges, and open areas across Massachusetts.
Why do so many birch species have pale bark? Researchers hypothesize that the white bark of gray birch, paper birch (Betula papyrifera), and other species provides an adaptive advantage in colder climates. Able to reflect sunlight, pale bark avoids big temperature swings in midwinter, reducing the trees’ risk of frost cracks. For this reason, several birch species reach the northernmost limits of tree growth in North America, one of the few types of deciduous trees that can do this.
Gray birch also provides considerable sustenance to wildlife. The seeds in its catkins feed overwintering and migrating birds and its fine branches and twigs supply good nesting sites. Many kinds of insects eat its leaves and catkins. In fact, the genus Betula hosts approximately 400 species of caterpillars, making birches among the top Lepidopteran host plants to introduce into your New England garden.