Ontario Trees & Shrubs website

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

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

  
The birches, to me, are almost as interesting as the maples, and that’s saying a lot. The Betulaceae clan, as the whole family is called in Latin, includes alders, birches, hornbeams, filberts and hazels. There are so many interesting things to say about each of these trees, that each deserves its own article. This is a look at the bark and other identifying characteristics of the major birches found in the Northeast.

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.

 
picture: Yellow birch’s catkins and last year’s leaves. Bartlett Arboretum, Stamford CT, Feb. 2005. Most birch leaves are double-toothed with parallel veins in a “V’ running straight to the leaf edge. The yellow’s have finer teeth, a tapering point, and alternate leaf veins. 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. Note also the shiny, reddish and slightly warty twigs.
 
Up-town you find the yellow (Betula alleghaniensis f/k/a B. Lutea) and black (Betula lenta) birches, tall trees of the deep forest that don’t come downtown. They are highly prized for their hardwood and much encouraged by foresters. Downtown are the white-bark birches prized by landscape architects and designers. The white-trunked ones include the native paper (Betula papyriera) and gray (Betula populifolia) birches, the naturalized European birch, and a handful of lesser-known nursery stock hybrids, dwarfs, and imports. The downtown crowd also includes the poodle-shaggy river birch (Betula nigra) (also called the red birch). The native and naturalized downtowners are also found in sunny spots up-town and along the rivers and beaches.
 
picture: young paper birches strut their colors downtown, Prospect Street, Stamford Feb. 2005.
 
THE TRIALS AND TRIBULATIONS OF BIRCH IDENTIFICATION:

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.

 
picture: waterproof, rot-proof and totally gorgeous, the curling bark of a paper birch. 3rd Street Stamford Feb 2005.
 
THE SIX MAJOR NORTHEAST BIRCHES:

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).

 

pictures: paper birch in Spring and Fall, 3rd Street Stamford CT, 2004. Note last year’s drooping cone underneath the new spring leaves. Note next year’s male catkins still summer –green when the first leaves start to turn the birches’ classic fall yellow. Note also the warty twigs for which paper birches are famous.
 
picture: Pronounced black chevrons on the bark of a stand of young gray birches, Landmark Mall Stamford CT Feb. 2005. The bark does NOT curl.
 
pictures: young gray birches show their colors and demonstrate their non-dropping branches. The cones, through, do droop. Landmark Mall Stamford CT Feb. 2005
 

pictures: a young gray birch has smooth, mossy, scratched bark of; Mall Stamford CT Feb. 2005. Lovely markings of a mature gray, Prospect Street, Stamford CT Feb 2005
 
picture: The European birch has dark horizon marking and very few chevrons. Landmark Mall Stamford CT Feb. 2005.
 

pictures: The European birch has dark horizon marking and very few chevrons, drooping branches and drooping cones, Prospect Street, Stamford CT Feb. 2005
 
picture: European birch’s summer leaves and green cone Prospect Street, Stamford CT Feb. 2005.
 
picture: The river birch has dramatic red-orange-white bark that’s so colorful and curly that it looks like water-ruined paper. Hoyt Street Stamford CT Feb. 2005
 

pictures: bark of very young, young, and slightly older river birch. Note that the bark gets flatter and craggier with age. Prospect and Hoyt Streets Stamford CT 2004- 2005
 

pictures: River birch leaves. Look closely in the first pictures for the just- spent male catkins and the erect female one; the second picture shows the green cone, and the third the ripe cones. By birch standards, these cones are considered erect. Hoyt Street Stamford CT May – June 2004
 
picture: A young river birch just starting to exfoliate. Breath-taking. Prospect Street Stamford CT Feb. 2005
 
picture: The cherry-like bark of a black birch, Bartlett Arboretum, Stamford CT Jan. 2005.
 

pictures: The bark of a yellow birch persists on the forest floor long after the trunk has rotted away , the trunk-flare of a yellow birch Bartlett Arboretum, Stamford CT Summer 2004
 
picture: summer leaves of the yellow birch, Bartlett Arboretum, Stamford CT summer 2004
 
picture: bark of a yellow birch looks spray-painted gold. In some lights, it looks silver. Elegant. Bartlett Arboretum, Stamford CT Feb 2005
 
CULTURE: Up-town and downtown, birches don’t do drought, soggy soil, alkaline soil, road-side pollution, shade, or heat, particularly at their roots. They also self- prune, thank you. Birches like the cold of the north, and are generally found from about Zone 3 to Zone 7. When the least bit unhappy, birches pick up a host of pests, the most serious being the dreaded (and often fatal) bronze birch borer. So, do not plant a birch unless you have a sunny site, at least 10 feet from the road, and are willing to water during droughts. Even then, the downtowners only live about 30 years in “captivity”.

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.

 

pictures: winter view of male catkins of paper and European birches. Stamford CT Feb 2005
 

pictures: winter view of male catkins of the gray and river birch. Most birches can have one to three male catkins on a branch tip. Stamford CT Feb. 2005; spring view of flowering male catkins of a paper birch 3rd Street Stamford CT spring 2004
  
From The Monday Garden. Copyright © by Sue Sweeney. Reproduced with permission. 

More articles from The Monday Garden

"The Monday Garden" is a FREE email publication published by Sue Sweeney. Visit The Monday Garden website