1311 Betula populifoliaCommon Names: gray birch,fire birch,old field birch,poplar birch Family: Betulaceae (birch Family)
Gray birch is a smallish tree that develops a narrow conical shape in maturity. It often has multiple stems, like a shrub, and will spread from suckers to take over an open area. A mature gray birch will be 20-40 ft (6-12 m) tall with a spread about 10 ft (3 m) across. The bark is a chalky grayish white and doesn’t peel as do most other birches. Beneath where each branch come off the trunk there is a characteristic V-shaped dark patch. Smaller branches and twigs hang downward and are decorated with wartlike protuberances. The leaves are diamond shaped, around 3-4 in (7-10 cm) long, with acuminate (long pointed) tips. They have teeth on their margins, and are glossy yellowish green, usually turning pure yellow in autumn. Male flowers are in pendant catkins carried singly (rarely doubly) at the ends of branches. They are yellowish brown, and about 3 in (7 cm) long. Female catkins (borne on the same plants) are shorter and greenish, and erect at first. Fruits are drooping cylindrical conelike catkins, about an inch (2.5 cm) long, containing numerous small winged nutlets.
A handful of cultivars have been named. ‘Lanciniata’ has pinnately lobed leaves. ‘Pendula’ has drooping branches. ‘Purpurea’ has purplish new growth.
Betula populifolia is native to northeastern North America, especially in Nova Scotia, Quebec, Ontario and New England. Scattered populations are found as far west as northern Illinois and as far south as northern Virginia. Gray birch often forms thickets, and can establish pure stands quickly in abandoned fields and recently burned over woods or clear-cut timber lands.
Light: Grow gray birch in full sun northward and part shade southward within its useful range. Moisture: Gray birch likes a moist soil that is well drained, and can tolerate short periods of wet soil. A good mulch cover over the roots protects from drying out and getting too hot in summer. Hardiness: USDA Zones 3 - 6 . Gray birch does best where summer temperatures rarely exceed 75° F (24° C), and winters get a good snow cover. Where summer temperatures are high, grow in partial shade and be sure to mulch the root zone and water regularly. Propagation: Sow fresh seed as soon as ripe outdoors in autumn. Keep seeds moist and in the shade. Root fast growing softwood cuttings under mist in spring or summer.
The gray birch is a fast growing little tree, up to 2-3 ft (60-90 cm) per year; but often short lived, to just 20 or 30 years. It tolerates poor soils, including those that are sandy or gravelly, and moist or dry. This is a nice graceful little tree for a specimen planting in a small yard. It has a tendency to grow multiple stems, but can easily be kept pruned to a standard single leader. The chalky bark is attractive in all seasons, and the male catkins are showy in spring. Fall foliage is often noteworthy. Gray birch leafs out early in spring and can be quite charming at that time. Some gardeners allow gray birch to naturalize in woodland gardens. Gray birch does not tolerate competition, though, so don’t try to grow it under larger trees. Gray birch is a perfect tree for a rain garden. Deer seem to avoid it.
Gray birch is an early successional stage “pioneer” tree that colonizes newly opened gaps (from fire or blow-downs) in the forest before trees characteristic of mature forests take over. Foresters refer to gray birch as an “intolerant” tree: it does not tolerate shade. Stands of gray birch act as nurseries for “tolerant” tree species normally found in mature forests and whose seedlings do tolerate shade, such as sugar maple (Acer saccharum), balsam fir (Abies balsamea), white spruce (Picea glauca), black spruce (P. mariana), red spruce (P. rubens), northern white cedar (Thuja occidentalis), and eastern hemlock (Tsuga canadensis), as well as several species of oak (Quercus), maple (Acer), and pine (Pinus). Seedlings of these tolerant tree species eventually grow up, close the gaps, and shade out the gray birches.
Steve Christman 6/20/18