The Monday Garden
Great Americans: Birches (The Winter View)

Issue No. 152 - February 20, 2005
by Sue Sweeney

In North America, we have 20 or so native birches, plus a bunch of imports, one of which, the European (Betula pendula), has widely “naturalized” in the Northeast and Northwest. In my part of sub/urbia, birches divide roughly into the downtown crowd of black-and-white dressing, fussy, fast-living, slender, graceful small-to-medium trees found near the malls and high-rises, and the up-town crowd of majestic, if equally fussy, slow-growing, long-lived valuable hardwood trees that grow in the forests north of town where private houses are built on lots measured in acres.

The North American birch family isn’t all the big, and the classic forms of various species are distinct. However, identification can be difficult due to name confusion, crossbreeding, hybridizing, and the introduction of foreign “ringers”. The birch names are, frankly, all screwed up. The common names are often colors such as red, gray, black, yellow and silver. However, there’s a lot of cross-over of the common names, so, for example, both the Betula populifolia and the Betula lenta are called “gray birch”. If that wasn’t confusing enough, a lot of the scientific names have been changed, so different sources use different scientific names and argue over them. Then, the tendency of the birches to crossbreed (and of plant nurseries to hybridize) gives you trees with characteristics of more than one type of birch. Oye! Lastly, the landscapers have included foreign birches in the mix and there are about 135 birches worldwide to choose from. For example, I just saw a row of cute little saplings a few blocks from here that I thought were paper birches due to the white, curling bark and the “Y” shape of the trunk and main branches; however, the planter had thoughtfully (sloppily?) left on the tags which said that they’re Himalayan birches.

Despite all of this, you can develop enough “birch sense” to know you’re looking at a birch, not a cherry (Rosaceae family) or an aspen or poplar (willow or Salicaceae clan), and to be pretty sure which type of birch. Most of the story is in the bark, the leaves, and the growth habit.

So some starter questions are:

What color is the bark? Does it curl? What kind of markings does the bark have?
Does the tree have catkins present? Are the catkins and cones erect or drooping?
Do the young branches and twigs droop (weep)?
What shape are the leaves? Do they have teeth?

A good way to do the identification is to go by the bark and then confirm (or disprove) your tentative ID by checking two or three other characteristics of the tree. Birch bark for the most part is white and chalky or shiny, and has pronounced horizontal bands of lenticels (pores). One of the few other tree families with shiny bark and horizontal bands of lenticels are cherries. Cherries, though, tend to gray or reddish bark with craggy, vertical fissures, the tree’s form is very different, and cherries have flowers, not catkins. Aspen leaves do look a bit like some birch leaves and the young bark may be white but check the trunk – aspens have completely different mature bark.

Paper birch: white, curling bark, bark has a chalky covering that rubs off easily; leaves round at the base with a pointed tip. Young trees are red-brown; turning white at about 4 years. Best native downtown tree and a better urban choice than the European, according to several sources. Cones droop.

Gray birch: white bark with black chevron (up-side down “v”) markings, not curling. Branches do not droop. Cones do. Leaf has a long point and flat base.

European birch (naturalized) : white bark with black horizontal markings (not usually chevron-shaped), not curling. Young branches, twigs, and cones droop. Leaves are triangular, leaf base may be notched.

River or Red birch: reddish or orange bark and so curly that it looks like ruined paper; bark becomes smooth and craggy with age. Deeply toothed leaves, pointed at both ends. Good for wet places. Cones erect (more or less).

Yellow birch: tall forest tree; bark color is gold or silver, shiny and peeling. The leaf has fine double teeth, alternate veins, and a pointed, tapering end; it may be notched at the base with the right side longer than the left. Cones erect (more or less).

Black birch: tall forest tree; the tree is also called the “cheery birch” because its bark so resembles that of a cherry-- shiny texture and horizontal lenticels, gray to black in color and vertically fissured like a cherry. Unlike a cherry, it’s very tall and straight, and has catkins. The leaf has very fine double teeth, opposite veins, and a pointed end; it may be notched at the base with the left side longer than the right. Cones erect (more or less).

WILDLIFE: Up-town, if the deer don’t get your birches, the porcupines, moose or rabbits probably will unless you plant enough for them and you. Luna moth children (larvae) feed on birch leaves as do a host of other insects. The elusive yellow-bellied sapsucker likes to make holes in the trunks (that is, when it’s not beating up on the sweet gum trees). Even the diminutive red squirrels are reported to be tree-girdling birch killers.

I guess the critters like the wintergreen flavor and sugary sap as much as humans do. Both up-town and downtown, birch seeds and catkins feed the small critters. Squirrels like to cache the catkins.

The life of a birch is a hard one and the fast-growing downtowners, exposed to pollution and poor growing conditions, as well as hungry wildlife, often don’t live long. Even the slow-growing up-towners loose a disproportionate number of their children to deer and the like.

HUMAN USE: In addition to landscaping, we use birches in medicine and food (especially the wintergreen flavoring). The up-towners yield first class hardwood. The bark is flexible, waterproof and doesn’t rot, so it’s great to make things.

Now, for a look at the male birch catkins. The male catkins on most birches come in groups of 1 to 3 at the branch tip; they are generally formed in the summer, stay on the tree of over the winter and bloom in the spring. The female catkins, which turn into green-then-brown cones, are shorter and further up the twig. The cones also persist on the branch often shedding seeds through winter.