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American woody plant expert Michael Dirr of the University of Georgia sometimes refers to birch trees as "ladies of the northern forest." These deciduous trees' upright, often light-coloured bark looks attractive during the long, cold winters when no leaves are present. Two birch species with light bark include the white birch (Betula populifolia) and the silver birch (B. pendula), also called the European white birch. Using only common names to discuss and compare birch species is problematic, as the white birch is sometimes called the grey birch. Both trees display nonpeeling grey-white to pure white bark.
The white birch is native to the cool climates of northeastern North America. Its natural range extends from Nova Scotia to Ontario south only as far as Delaware. It usually is among the first trees to populate a cleared forest area in these regions on any type of acidic soil. By contrast, the silver birch hails from Eurasia. It grows naturally in continental Europe north of the Alps and eastward across Russia into the highest mountain elevations in central Asia and Siberia.
Size and Habit
The white birch readily develops a multitrunked silhouette that is upright but narrow. Mature trees range from 20 to 40 feet tall but only 10 to 20 feet wide. The tree's canopy is irregular and open-branched, and looks somewhat pointed at the tree's top. The silver birch becomes a much larger tree, usually with one central trunk. In its native lands, silver birch matures up to 100 feet tall, but dimensions of 40 to 60 feet tall and 25 to 40 feet wide are typical in garden settings. When young, the tree is an almost perfect triangle, and then becomes more oval with a triangular tip when mature.
Both white and silver birch trees produce pointed dark green leaves that are 1 to 3 inches long. The leaves display double-serrated edges and are wide and nearly heartlike at their bases, but quickly narrow and taper to a point. White birch trees leaf out slightly earlier in the spring than silver birch. Silver birch's male catkin flower clusters usually occur in clusters of two, whereas in the white birch they occur singly. Both birch trees produce yellow fall foliage. Silver birch displays more reliable, intensely bright yellow foliage, and white birch's display is attractive but less showy, with only a yellow-green hue.
Grow both white and silver birch in U.S. Department of Agriculture Plant Hardiness Zone 2 through Zone 6. Silver birch is a bit more tolerant of summer heat, but the tree still looks ghastly. Plant both trees in full sun. Silver birch grows best in a cool, moist soil, while white birch must have an acidic soil, but it tolerates sandy and gravelly dry sites extremely well. Both of these birch trees are susceptible to bronze birch borer insect damage in North America. However, silver birch sustains significantly worse damage, even death, as a result of a borer infestation. White birch looks haggard and sickly after being infested by borers, but it usually survives. White birch's worst issue is leaf miner infestations.
- "Dirr's Hardy Trees and Shrubs"; Michael A. Dirr; 1997
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