Even thirty years ago, almost every Finn could tell you the difference between silver birch and downy birch (Betula pendula and Betula pubescens). The identification of plant species was part of basic education and at the very least, it was believed that the birch should be distinguished from each other so that proper whisks could be made for the sauna. Silver birch is for the branches and leaves of the whisk, which are then tied with downy birch. It is possible to identify the species on the basis of differences in the structure of leaves, branches and trunk. The leaves of the silver birch are triangular to diamond-shaped and doubly serrated; there are large veins and small teeth between them. The leaf of the downy birch is ovate with fine hair and the edges of the leaf are only serrated. The new leaves of the downy birch are fine haired and soft while the silver birch’s is rough and noduled. The difference is noticeably clear when drawing one’s fingers over the adult leaf. The trunk of the silver birch has older, horizontal fissure bark while the downy birch’s bark is often flaky. Unfortunately, both types of birch vary considerably and the differences are not always clear. Determining which birch is which is also complicated by the fact that they easily cross-pollinate and create hybrid specimens, meaning a tree can have the characteristics of both.
Some birch trees are easy to identify by simply examining their general shape. Almost all of the hanging branch birch trees are silver birch trees while the same shape is extremely rare for downy birch. Also, the place of growth can reveal which birch tree you are looking at: downy birch favour exposed places near shorelines and swampy areas. Silver birch, on the other hand, favour good and nutritious growing habitats. The silver birch is the more common species but both birch trees grow in Myllylähde’s environs.
Photo: Jyrki Oja