Tree of the week for January 16th-23rd, 2011: Betula populifolia
"The traveler who enters New England for the first time sees from his train or car window, in every abandoned field, on every dry and gravelly slope around the margins of swamps, and springing up beside the rambling stone walls, a little tree over 30 feet tall and commonly only 15 to 20 feet, with a spindling stem and Aspen-like, fluttering foliage." This is how Peattie introduces this week's tree, emphasizing both its ubiquity in those areas where it is to be found, and its uniqueness to those regions. It is a die-hard Yankee, this week's tree, and one of the Mainer's surest, most refreshing companions through the long dark winter. The tree I am speaking of is the...
Gray Birch, Betula populifolia
Synonyms: Fire birch, white birch, blue birch. I've never actually heard anyone call the tree one of these names though.
Range and Habitat: As mentioned above, the gray birch is a die-hard Yankee. In New England & New York it is terribly common, as it is in the warmer, more habitable parts of the Canadian maritimes & Québec. But if one moves south or west of these regions, the tree becomes rarer and rarer, disappearing entirely by the time one hits Chesapeake Bay, and only found in a few isolated spots west of Lake Huron.
This range has expanded somewhat, however. Increasing human activity in the Gaspé Peninsula1 and other parts of eastern Canada is allowing the birch to move north, colonizing mined-over peatlands, old fields, and other pieces of anthropogenic wasteland. At the same time, the tree's handsomeness has made it appeal to gardeners and landscapers, who have planted it in a broad band westwards across the continent. Predictably, in some areas it has escaped from cultivation, especially in the wetter regions of the Midwest most strongly affected by the Great Lakes.
Native? Y/N: Y
Plant ID: The tree is very clearly a birch, with its bone-white bark; slender, drooping, whip-like limbs; and dagger-like leaves2. The botanically innocent may be apt to confuse it with the celebrated paper birch3, but there is no reason for this confusion. For the gray birch's bark does not peel as often as its relative's. Even when it does peel, it comes off in small strips rather than in broad sheets. Also, the leaves of gray birch come to a much more dramatically sharp point. The tree may be identified from a distance, even in winter, by its habit of always throwing up multiple trunks from the ground, and by its thin, whip-like branches.
Ecology: B. populifolia is a tree of young forests. When the farmer abandons her field, or when fire sears the forest, it is one of the first woody plants to sprout up. It grows quite rapidly, but also dies young; a fifty year old tree is already well into its dotage. According to the common wisdom among foresters, other more shade-tolerant species of trees soon succeed the birches, coming up in their shade eventually to overtop and dominate them. But in my opinion, the ability of gray birch to occupy land for a long time is not to be underestimated. The tree can produce a surprising amount of shade, and its roots are aggressive enough to actively impede the establishment of other trees. And when a gray birch does die, the stand is usually so densely stocked with gray birches that their seeds will be littering the ground where the dead tree stood so its most likely replacement will be another gray birch. Furthermore, the tree has significant powers of vegetative reproduction, so a dead tree may well be replaced by its own suckers. Again, it should be noted that this is my own hypothesis, not one general to the scientific community. But I have heard anecdotal reports from the wood-wise of gray birch stands that have remained unmoved for some seven or eight decades, well beyond the life of most of their individual trees.
The gray birch puts so much of its energy into growth that it does not have terribly active defense strategies vis-á-vis insect and fungal pests, and so is quite susceptible to them. One of the most serious of these is the bronze birch borer, a native species of beetle that eats the tree's sap and living wood (phloem). Much has been made of this insect because of the damage it can do to pampered ornamental birches in yards and gardens. But gray birch is hardy to it, and only succumbs when it is under some other stress, especially a lack of water. The birch's general attractiveness to insects, though, does have one benefit: it attracts the birds who in turn feed on the insects, as reported here.
Uses and Silviculture: New England's lumbermen and foresters consider this tree a frank nuisance in the best of times. Its wood might be of some use, as that of its close relatives the paper birch and yellow birch is, but the tree is too small and spindly to be milled. One cannot make boards from a trunk four inches in diameter at its widest! As far as they are concerned, it merely takes up acreage that might otherwise be occupied by more valuable species.
While this author understands such an opinion, there is nevertheless much to say for B. populifolia from even the most utilitarian of perspectives. The hunter, for instance, has a much higher opinion of the tree. After all, the deer that she hunts much prefer the leaves and inner bark of this tree to the resin-infused organs of the conifers that most frequently replace it. And likewise the forager, who knows that its sap may be used as a delightful flavoring agent, for instance in birch beer. Eflora's Flora of North America further reports that the Micmac used some part of the gray birch as an antiseptic on infected wounds, but sadly do not give further details. Finally, the wood of the gray birch, like that of all birches, has a very high caloric content, and so makes an excellent fire. According to Wikipedia, it will even burn well when wet, thanks to some of the essential oils it contains.
Taxonomy: Betula is such a prominent member of north-temperate and boreal forests that its whole family, the Betulaceae, is named after it. The Betulaceae also contains the alders, the hornbeams and hop-hornbeams, and the hazels. It is one of those rare family whose members all truly do look alike. They are almost uniformly graceful plants, with thin whip-like branches that curve and arc, and have a tendency to grow where few other trees will. Thus do they beautify otherwise harsh landscapes, whether the snowy lands of Québec and Scandinavia (birches), the huge swamps of the Baltic coasts (alders), or the dry and stony mountains of the middle east (hazels).
Beautifying otherwise harsh landscapes since 1986,
--mark
1 Map courtesy of New England Seabirds.
2 Image courtesy of Virginia Tech's Department of Forest Resources.
3 Image courtesy of the University of Alaska at Fairbanks.
Gray Birch, Betula populifolia
Synonyms: Fire birch, white birch, blue birch. I've never actually heard anyone call the tree one of these names though.
Range and Habitat: As mentioned above, the gray birch is a die-hard Yankee. In New England & New York it is terribly common, as it is in the warmer, more habitable parts of the Canadian maritimes & Québec. But if one moves south or west of these regions, the tree becomes rarer and rarer, disappearing entirely by the time one hits Chesapeake Bay, and only found in a few isolated spots west of Lake Huron.
This range has expanded somewhat, however. Increasing human activity in the Gaspé Peninsula1 and other parts of eastern Canada is allowing the birch to move north, colonizing mined-over peatlands, old fields, and other pieces of anthropogenic wasteland. At the same time, the tree's handsomeness has made it appeal to gardeners and landscapers, who have planted it in a broad band westwards across the continent. Predictably, in some areas it has escaped from cultivation, especially in the wetter regions of the Midwest most strongly affected by the Great Lakes.
Native? Y/N: Y
Plant ID: The tree is very clearly a birch, with its bone-white bark; slender, drooping, whip-like limbs; and dagger-like leaves2. The botanically innocent may be apt to confuse it with the celebrated paper birch3, but there is no reason for this confusion. For the gray birch's bark does not peel as often as its relative's. Even when it does peel, it comes off in small strips rather than in broad sheets. Also, the leaves of gray birch come to a much more dramatically sharp point. The tree may be identified from a distance, even in winter, by its habit of always throwing up multiple trunks from the ground, and by its thin, whip-like branches.
Ecology: B. populifolia is a tree of young forests. When the farmer abandons her field, or when fire sears the forest, it is one of the first woody plants to sprout up. It grows quite rapidly, but also dies young; a fifty year old tree is already well into its dotage. According to the common wisdom among foresters, other more shade-tolerant species of trees soon succeed the birches, coming up in their shade eventually to overtop and dominate them. But in my opinion, the ability of gray birch to occupy land for a long time is not to be underestimated. The tree can produce a surprising amount of shade, and its roots are aggressive enough to actively impede the establishment of other trees. And when a gray birch does die, the stand is usually so densely stocked with gray birches that their seeds will be littering the ground where the dead tree stood so its most likely replacement will be another gray birch. Furthermore, the tree has significant powers of vegetative reproduction, so a dead tree may well be replaced by its own suckers. Again, it should be noted that this is my own hypothesis, not one general to the scientific community. But I have heard anecdotal reports from the wood-wise of gray birch stands that have remained unmoved for some seven or eight decades, well beyond the life of most of their individual trees.
The gray birch puts so much of its energy into growth that it does not have terribly active defense strategies vis-á-vis insect and fungal pests, and so is quite susceptible to them. One of the most serious of these is the bronze birch borer, a native species of beetle that eats the tree's sap and living wood (phloem). Much has been made of this insect because of the damage it can do to pampered ornamental birches in yards and gardens. But gray birch is hardy to it, and only succumbs when it is under some other stress, especially a lack of water. The birch's general attractiveness to insects, though, does have one benefit: it attracts the birds who in turn feed on the insects, as reported here.
Uses and Silviculture: New England's lumbermen and foresters consider this tree a frank nuisance in the best of times. Its wood might be of some use, as that of its close relatives the paper birch and yellow birch is, but the tree is too small and spindly to be milled. One cannot make boards from a trunk four inches in diameter at its widest! As far as they are concerned, it merely takes up acreage that might otherwise be occupied by more valuable species.
While this author understands such an opinion, there is nevertheless much to say for B. populifolia from even the most utilitarian of perspectives. The hunter, for instance, has a much higher opinion of the tree. After all, the deer that she hunts much prefer the leaves and inner bark of this tree to the resin-infused organs of the conifers that most frequently replace it. And likewise the forager, who knows that its sap may be used as a delightful flavoring agent, for instance in birch beer. Eflora's Flora of North America further reports that the Micmac used some part of the gray birch as an antiseptic on infected wounds, but sadly do not give further details. Finally, the wood of the gray birch, like that of all birches, has a very high caloric content, and so makes an excellent fire. According to Wikipedia, it will even burn well when wet, thanks to some of the essential oils it contains.
Taxonomy: Betula is such a prominent member of north-temperate and boreal forests that its whole family, the Betulaceae, is named after it. The Betulaceae also contains the alders, the hornbeams and hop-hornbeams, and the hazels. It is one of those rare family whose members all truly do look alike. They are almost uniformly graceful plants, with thin whip-like branches that curve and arc, and have a tendency to grow where few other trees will. Thus do they beautify otherwise harsh landscapes, whether the snowy lands of Québec and Scandinavia (birches), the huge swamps of the Baltic coasts (alders), or the dry and stony mountains of the middle east (hazels).
Beautifying otherwise harsh landscapes since 1986,
--mark
1 Map courtesy of New England Seabirds.
2 Image courtesy of Virginia Tech's Department of Forest Resources.
3 Image courtesy of the University of Alaska at Fairbanks.