Five species of birch are native to Minnesota. All can be told apart by their bark and leaf shape. The most common is the iconic paper birch (Betula papyrifera), but the largest and most majestic is the yellow birch. In Minnesota, it can grow to nearly 100 feet in height and have a trunk 4 feet in diameter. When young, the bark is golden yellow and has a metallic sheen. The outer layer peels in thin papery strips or shreds like shavings from a carpenter's plane, giving the tree a shaggy look. The bark of older trees often becomes gray and loses its papery texture. The leaves are oval in outline, with a pointed tip and sharply double-serrated margins. If identification is in doubt, scrape a twig with your thumbnail. The sap will have the distinct smell of wintergreen.
Yellow birch occurs in cool, northern forests in a band just south of the great boreal forest of Canada. It is found from the Maritime Provinces in the east to Minnesota in the west. It ranges south only in the Adirondack Mountains. In Minnesota it can be found throughout the forested region of the state, but it is somewhat of an oddity south of the Twin Cities, where it might be found as scattered solitary trees on cool, north-facing, forested slopes. In northern Minnesota it is less rare, but still not abundant. In that region it is most often found in cool swamps with northern white cedar, and in moist uplands with sugar maple and white spruce.
The familiar paper birch is common in young, second-growth forests where sunlight is often plentiful. As the forest matures, the sunlight reaching the forest floor dims and young paper birch fail to mature. Only a few tree species can survive under such conditions, and yellow birch is one of them. It does this with a few tricks all its own.
Unlike paper birch, the seeds of yellow birch don't need bare soil. Instead, they may germinate on a mossy boulder and send their roots over the sides until they reach the soil. Eventually, the tree may nearly encase the boulder. If a mossy boulder isn't available, yellow birch seeds may germinate on a fallen log, called a nurse log, sending roots over the log and into the soil. When the log eventually rots away, the yellow birch will appear to be perched above the ground on stilts. Even these strangely formed trees can rise to the canopy of an old-growth forest and live 300 years or more.
Yellow birch is often said to have the finest wood of all the birches, and it is prized in the lumber trade. But very little yellow birch is cut in Minnesota. It is simply too scattered and remote. Because they take so long to mature, large yellow birch trees are now mostly limited to protected areas such as state parks.