However, the potency of the odor is not considered a reliable identification method unless it is combined with other characteristics. The leaves are alternately placed on the stem, oval in shape with a pointed tip and often a slightly heart shaped (cordate) base. They are long and typically half as wide with a finely serrated (doubly serrate) margin. They are dark green in color on the upper side and lighter on the bottom, the veins on the bottom are also pubescent. The leaves arise in pairs or singularly from small spur shoots. In the fall the leaves turn a bright yellow color. The leaf has a very short petiole long. The flowers are wind-pollinated catkins which open in later spring. Both male and female flowers will occur on the same tree making the plant monoecious. The male catkins are long, yellow purple, pendulous (hang downwards), and occur in groups of 3-6 on the previous year's growth. The female catkins are erect (point upward) and long and oval in shape, they arise from short spur branches with the leaves. The fruit, mature in fall, is composed of numerous tiny winged seeds packed between the catkin bracts. The seed is a winged samara with two wings which are shorter than the width of the seed which matures and gets released in autumn. Similarity to Betula lenta Both yellow birch and sweet birch have nearly identical leaf shape and both give an odor of wintergreen when crushed. Seedlings of the two species can be very hard to tell apart. To differentiate the two, the range, buds, or bark must be examined. The ranges do overlap in Appalachia where they commonly grow together, but sweet birch does not grow west of Ohio or north into Canada whereas yellow birch does. Sweet birch also has black non-peeling bark compared to the lighter, bronze colored, peeling bark of yellow birch. For young trees where bark has not yet developed, yellow birch can also be identified by its hairy buds and stems; sweet birch has hairless buds. Taxonomy The yellow birch was first described by François André Michaux in 1812 as Betula lutea. In 1904, Nathaniel Lord Britton described what he considered to be a new closely related species of birch as Betula alleghaniensis, differing from B. lutea by its shorter fruiting scales and mostly cordate (vs. rarely cordate) leaf bases. After comparing the descriptions and illustrations