Betula alleghaniensis, the yellow birch, golden birch, or swamp birch, is a large and important lumber species of birch native to North-eastern North America. Its vernacular names refer to the golden color of the tree's bark. The name Betula lutea was used expansively for this tree but has now been replaced.
Betula alleghaniensis is the provincial tree of Quebec, where it is commonly called merisier, a name which in France is used for the wild cherry.
This tree is typically 60-75' tall at maturity with a single trunk that spans up to 3½' across. In open areas, the crown is large and widely spreading, while in dense forested areas it is small and irregular. For the typical variety of Yellow Birch, trunk bark is grayish yellow to bronze and somewhat lustrous, peeling away in papery sheets that are curled along their margins. For a more southern variety (var. fallax), trunk bark is gray to dark brown and wrinkled; it does not exfoliate to the same extent as the bark for the typical variety of this tree. The bark of branches and twigs is reddish brown, brown, or gray with scattered white lenticels; their inner bark has a mild wintergreen aroma. Young shoots and spur shoots are light green and usually pubescent. The leaves are arranged alternately along the twigs on short spur-shoots; there are one or two leaves per spur-shoot. The leaf blades are 2½-4" long and 1¼-2½" across; they are ovate in shape and doubly serrated along their margins. The upper surface of these blades is dark green and either glabrous or sparsely covered with short stiff hairs; the lower surface is medium green and pubescent along the veins. The petioles are ¼-½" long, pale green, and short-pubescent.
Yellow Birch is monoecious, forming male (staminate) and female (pistillate) catkins on the same tree. Male catkins occur at the tips of last year's twigs in groups of 3-6. During the blooming period, they droop downward and become 2½-4" long. At this time, the male catkins are narrowly cylindrical and yellowish purple. Each male catkin consists of numerous male florets and their bracts. Male florets occur in groups of 3 behind each bract; each male floret consists of 2 stamens. Each bract is oval-orbicular in shape and ciliate along its margins. Female catkins occur individually on short spur-twigs near the petioles of leaves; they are sessile or nearly so. The female catkins are upright, ovoid-oblongoid in shape, and greenish, ultimately becoming ¾-1¼" in length at maturity. Each female catkins consists of numerous female florets and their bracts. Female florets occur in groups of 3 behind each bract; each female floret consists of a naked ovary and a pair of styles. The bracts are ¼-½" long, 3-lobed and ciliate along their margins. The blooming period occurs during late spring for about 1 week. The florets are cross-pollinated by the wind. The female catkins turn brown as their winged seeds (samaras) ripen. Each seed body is about 1/8" (3 mm.) long, ellipsoid-ovoid in shape, and somewhat flattened. Membranous wings extend on opposite sides of each seed; they are a little less wide than the seed body. The woody root system is relatively shallow and widely spreading. This tree reproduces by reseeding itself.
