Tree of the week for September 12th-19th, 2010: Juglans cinerea
I've been meaning to post this entry for, well, several months now, but have been stymied first by lack of photos, then by lack of camera cables, and then by simple laziness. But here it is, kiddies, so feel satisfied.
The tree I'm writing about is one of the U.S.'s rarer trees. This tree was never as celebrated as the American Chestnut, Castanea dentata, or the American Elm, Ulmus americana nor has it fallen quite so much as either of these, but still 'tis a beautiful tree that has nevertheless been devastated by a foreign fungus. Once, this was the nut tree of upper New England and Wisconsin, whose many virtues were a boon to human and beast alike. But now, the attractions of its beautiful wood and the canker Sirococcus lavigignenti-juglandacearum1 have reduced the population of this tree hugely. With all of this in mind, it was with some glee that I encountered a decent number of these plants surviving in the Mount Washington Valley region this summer. This of course inspired me to write about our Tree of the Week, the protagonist of this sad tale...
Butternut, Juglans cinerea
Synonyms: "White walnut"
Range and Habitat: The white walnut's range is roughly coterminous with the boundaries of the Laurentian (Humid Continental, or "hot summer" continental) climate zone in North America. The only significant exception to this general rule is the northern boundary of the butternut's range, which is determined rather by the annual minimum temperature. Butternut cannot survive temperatures below -30 F (USDA zone 4a), and lo and behold! Its northern boundary2 is indeed similar to that of USDA zone 4a3.
Within this range, butternut loves very deep, well-drained but also well-watered soils. It grows better on droughty sites than many of its associates, but not nearly well enough to compete with the real lovers of sandy soils, the hard pines, red oaks and heath family shrubs. It is quite intolerant of shade, and so is generally found on forest edges, stream banks, and woody meadows.
Native? Y/N: Y No less an authority than Peattie describes butternut as a "grand old American" and a "uniquely American wood".
Plant ID: Butternut, like all walnuts, has long, compound leaves4 that either do not have a terminal leaflet, or have a terminal leaflet that is much smaller than the other leaflets. These leaves tend to be arranged in large, drooping clusters at various points on the branches. They are technically alternate, but their strongly clustered arrangement tends to mask this fact. The bark of the tree is a pale gray, and has many broad ridges and fissures arranged in a rather chaotic manner up and down the trunk. These give the tree a rugged, agéd appearance even when small, like a Montanan or Mongolian cowherd with dust-blasted and deep crow's-feet 'round his eyes.
Its flowers, which it produces in late spring, are very small5 and almost invisible from the ground. Over the course of the summer and early fall, these develop into large, green football-shaped walnuts5.
Butternut is not a particularly large tree, normally growing to some fifty or sixty feet at maturity, and with a maximum size of seventy-five or eighty feet. It begins branching fairly low down along the trunk, but these early branches grow rather thickly themselves and ascend sharply, practically forming secondary trunks which themselves branch quite infrequently. Despite these generalizations, J. cinerea's upper height limit is hard to determine, considering how devastated butternut has been by butternut canker, and how slow-growing it is. The ENTS crew have, on their tall tree list, records of several butternuts above 100' in height, in places as far apart as Massachusetts, Pennsylvania and Tennessee. These trees seem quite exceptional in relation to those I saw in Fryeburg, but the Federal Silvics Manual claims that 100' is the expected height of "mature trees".
Ecology: At the moment, J. cinerea's ecology is dominated by the existence of the butternut canker. This disease first appeared at some time in the 1960s, tho' I can find no information where it came from. It is a fungus whose spores, carried by the wind, infect any opening in the butternut's protective bark. Most commonly this will be a leaf scar or bud, and so the disease starts in one of the trees branches. The branch will typically die before the canker can spread into the trunk, but the crafty fungus' spores will be washed onto the trunk and ground by rainwater. Then, it soon spreads into the roots and lower trunk of the plant, forming a series of cankers6 underneath the bark of the tree that eventually girdle the tree and kill it. First some of the branches die, then more, then more and more until the tree is just a barren, ash-gray skeleton. And since the fungus can get into the roots, butternut, which doesn't sprout very vigorously even in the best of times, is unable to produce any new shoots after the death of the main trunk. This disease has been especially devastating to the plant in the warmer, southern parts of its range. The canker, apparently, is more vulnerable to frost than its host is, and this has given those living further north some resistance, though not enough to save them from a great reduction in numbers.
In better times, though, butternut is a tree of riparian areas and hillsides. Never common, it is yet able to fight out a niche for itself among more shade-tolerant trees by producing a chemical called juglone that interferes with the metabolism of surrounding trees, inhibiting their growth. At the same time, its both deep and wide root system makes it very competitive for water and nutrients underground. Its fruits are harvested and buried with great assiduity by squirrels, just like acorns are, and the sheer size of the fruits means that those forgotten by squirrels are given a tremendous boost to their early life; butternuts have a rapid growth rate when young, though this drops off quickly.
Uses and Silviculture: In the days before its devastation, the white walnut had a bevy of uses. Never growing in dense stands, it was therefore largely ignored by the industrial lumber business. Instead, it was of great value to the general rural population. Its wood is very soft and easy to work, and so it found favor as a carving material with which to make a great many items. Also, it is said by Peattie to have a "satiny" texture that produces "an air of sumptuousness", and so has been valued in cabinetry and paneling of both humble and luxury varieties. Its inner bark, too, produces an orange-yellow dye that may be applied to cloth, and indeed during the Civil War some of the poorer Rebels wore rather non-uniform uniforms dyed in just that manner.
The walnuts made by the tree are said to taste sweet, and are very oily. They mature late in the fall, and I cannot say that I have ever had the pleasure of trying one. They are also said to become rancid very quickly if not stored properly, and so I cannot recommend them to any significant degree, despite their supposed deliciousness. Still, that deliciousness is of such a degree that they were used for candy, like peanuts or almonds, and I was able to find, without much searching, this recipe for butternut-maple fudge. Mmmm!
Taxonomy: Obviously, Juglans is the genus of all the walnuts, from the white walnut, to the Juglans regia we eat, to the Juglans nigra so valuable for cabinetry. The family they are in is named after them, too - the Juglandaceae. It also contains those most American of trees, the hickories, Carya, which grow only in the New World and have their greatest diversity in the hardwood forests of southern Illinois, eastern Missouri, and western Kentucky. The remainder of the family consists of trees of the tropical Americas and temperate-to-subtropical Asia, such as Alfaroa and the "wingnut" Pterocarya. While they are rather obscure trees from my perspective here in temperate North America, many of them are of considerable local importance, producing valuable timber and used as ornamentals.
Producing valuable timber and used as an ornamental since 1986,
--mark
1 Say that five times fast. I dare you.
2 Map courtesy of the USDA forest service.
3 Map accessed at the website of the U.S. National Arboretum.
4 Image courtesy of the Clay Hill Memorial Forest
5 Image courtesy of Forestry Images.
6 Image - and most of the information in this paragraph - from the USDA Forest Service.
The tree I'm writing about is one of the U.S.'s rarer trees. This tree was never as celebrated as the American Chestnut, Castanea dentata, or the American Elm, Ulmus americana nor has it fallen quite so much as either of these, but still 'tis a beautiful tree that has nevertheless been devastated by a foreign fungus. Once, this was the nut tree of upper New England and Wisconsin, whose many virtues were a boon to human and beast alike. But now, the attractions of its beautiful wood and the canker Sirococcus lavigignenti-juglandacearum1 have reduced the population of this tree hugely. With all of this in mind, it was with some glee that I encountered a decent number of these plants surviving in the Mount Washington Valley region this summer. This of course inspired me to write about our Tree of the Week, the protagonist of this sad tale...
Butternut, Juglans cinerea
Synonyms: "White walnut"
Range and Habitat: The white walnut's range is roughly coterminous with the boundaries of the Laurentian (Humid Continental, or "hot summer" continental) climate zone in North America. The only significant exception to this general rule is the northern boundary of the butternut's range, which is determined rather by the annual minimum temperature. Butternut cannot survive temperatures below -30 F (USDA zone 4a), and lo and behold! Its northern boundary2 is indeed similar to that of USDA zone 4a3.
Within this range, butternut loves very deep, well-drained but also well-watered soils. It grows better on droughty sites than many of its associates, but not nearly well enough to compete with the real lovers of sandy soils, the hard pines, red oaks and heath family shrubs. It is quite intolerant of shade, and so is generally found on forest edges, stream banks, and woody meadows.
Native? Y/N: Y No less an authority than Peattie describes butternut as a "grand old American" and a "uniquely American wood".
Plant ID: Butternut, like all walnuts, has long, compound leaves4 that either do not have a terminal leaflet, or have a terminal leaflet that is much smaller than the other leaflets. These leaves tend to be arranged in large, drooping clusters at various points on the branches. They are technically alternate, but their strongly clustered arrangement tends to mask this fact. The bark of the tree is a pale gray, and has many broad ridges and fissures arranged in a rather chaotic manner up and down the trunk. These give the tree a rugged, agéd appearance even when small, like a Montanan or Mongolian cowherd with dust-blasted and deep crow's-feet 'round his eyes.
Its flowers, which it produces in late spring, are very small5 and almost invisible from the ground. Over the course of the summer and early fall, these develop into large, green football-shaped walnuts5.
Butternut is not a particularly large tree, normally growing to some fifty or sixty feet at maturity, and with a maximum size of seventy-five or eighty feet. It begins branching fairly low down along the trunk, but these early branches grow rather thickly themselves and ascend sharply, practically forming secondary trunks which themselves branch quite infrequently. Despite these generalizations, J. cinerea's upper height limit is hard to determine, considering how devastated butternut has been by butternut canker, and how slow-growing it is. The ENTS crew have, on their tall tree list, records of several butternuts above 100' in height, in places as far apart as Massachusetts, Pennsylvania and Tennessee. These trees seem quite exceptional in relation to those I saw in Fryeburg, but the Federal Silvics Manual claims that 100' is the expected height of "mature trees".
Ecology: At the moment, J. cinerea's ecology is dominated by the existence of the butternut canker. This disease first appeared at some time in the 1960s, tho' I can find no information where it came from. It is a fungus whose spores, carried by the wind, infect any opening in the butternut's protective bark. Most commonly this will be a leaf scar or bud, and so the disease starts in one of the trees branches. The branch will typically die before the canker can spread into the trunk, but the crafty fungus' spores will be washed onto the trunk and ground by rainwater. Then, it soon spreads into the roots and lower trunk of the plant, forming a series of cankers6 underneath the bark of the tree that eventually girdle the tree and kill it. First some of the branches die, then more, then more and more until the tree is just a barren, ash-gray skeleton. And since the fungus can get into the roots, butternut, which doesn't sprout very vigorously even in the best of times, is unable to produce any new shoots after the death of the main trunk. This disease has been especially devastating to the plant in the warmer, southern parts of its range. The canker, apparently, is more vulnerable to frost than its host is, and this has given those living further north some resistance, though not enough to save them from a great reduction in numbers.
In better times, though, butternut is a tree of riparian areas and hillsides. Never common, it is yet able to fight out a niche for itself among more shade-tolerant trees by producing a chemical called juglone that interferes with the metabolism of surrounding trees, inhibiting their growth. At the same time, its both deep and wide root system makes it very competitive for water and nutrients underground. Its fruits are harvested and buried with great assiduity by squirrels, just like acorns are, and the sheer size of the fruits means that those forgotten by squirrels are given a tremendous boost to their early life; butternuts have a rapid growth rate when young, though this drops off quickly.
Uses and Silviculture: In the days before its devastation, the white walnut had a bevy of uses. Never growing in dense stands, it was therefore largely ignored by the industrial lumber business. Instead, it was of great value to the general rural population. Its wood is very soft and easy to work, and so it found favor as a carving material with which to make a great many items. Also, it is said by Peattie to have a "satiny" texture that produces "an air of sumptuousness", and so has been valued in cabinetry and paneling of both humble and luxury varieties. Its inner bark, too, produces an orange-yellow dye that may be applied to cloth, and indeed during the Civil War some of the poorer Rebels wore rather non-uniform uniforms dyed in just that manner.
The walnuts made by the tree are said to taste sweet, and are very oily. They mature late in the fall, and I cannot say that I have ever had the pleasure of trying one. They are also said to become rancid very quickly if not stored properly, and so I cannot recommend them to any significant degree, despite their supposed deliciousness. Still, that deliciousness is of such a degree that they were used for candy, like peanuts or almonds, and I was able to find, without much searching, this recipe for butternut-maple fudge. Mmmm!
Taxonomy: Obviously, Juglans is the genus of all the walnuts, from the white walnut, to the Juglans regia we eat, to the Juglans nigra so valuable for cabinetry. The family they are in is named after them, too - the Juglandaceae. It also contains those most American of trees, the hickories, Carya, which grow only in the New World and have their greatest diversity in the hardwood forests of southern Illinois, eastern Missouri, and western Kentucky. The remainder of the family consists of trees of the tropical Americas and temperate-to-subtropical Asia, such as Alfaroa and the "wingnut" Pterocarya. While they are rather obscure trees from my perspective here in temperate North America, many of them are of considerable local importance, producing valuable timber and used as ornamentals.
Producing valuable timber and used as an ornamental since 1986,
--mark
1 Say that five times fast. I dare you.
2 Map courtesy of the USDA forest service.
3 Map accessed at the website of the U.S. National Arboretum.
4 Image courtesy of the Clay Hill Memorial Forest
5 Image courtesy of Forestry Images.
6 Image - and most of the information in this paragraph - from the USDA Forest Service.