Black Locust (Robinia pseudoacacia) is a medium size tree. Native south of Michigan, its range reaches into southern Ohio. Planted to the north because its wood is used for fence posts, tool handles, and wheel hubs. Trees planted in rows along the edge of a field often served as living fence posts. It spreads by seeds and can send out suckers, forming large stands.
Black locust leaves and spinesBlack locust winter twigs
It is identified by its alternate, compound leaves that have entire (toothless) margins and twigs with a pair of spines at each node. Black Locust seedpods are smooth and resemble garden peapods. The racemes of white, fragrant flowers are pretty. Winter twigs have buds partly hidden under reddish-brown hairs.
Black locust seedpods and barkStand of Black locust along Lake Superior south shore
Black Locust occurs throughout the state. It is often seen in natural areas in southern Michigan and along the shores of the Great Lakes. Because of its suckering habit it out competes natives and can be challenging to eradicate.
Tree-of-Heaven (Ailanthus altissima) is a non-native, invasive, weed tree. With its fast growth and wide tolerance of growing conditions, Tree-of-Heaven was previously regarded as a desirable species. Reproducing by seeding and suckering, it aggressively colonizes open, sunny locations. This is a field or woodland edge species.
Tree-of-Heaven bark – L & M Smooth Sumac – RTree-of-Heaven seedsTree-of-Heaven twigs showing buds, lenticels and leaf scars
Large, foul smelling, pinnate compound leaves and commonly a reddish petiole help to determine this species. Gland tipped teeth occur at the base of the leaflets. Gray bark with short, vertical line-like ridges is distinctive. Fruit is single seeded in a twisted wing, up to 4.5 cm [1 ¾ inches] long, and sometimes it shows a reddish cast. Brownish, smooth, stout twigs with numerous lenticels and large leaf scars characterize Tree-of-Heaven.
Smooth SumacSmooth Sumac twig. bud, and leaf scar
Smooth Sumac (Rhus glabra) is a similar species that seldom attains tree size. It has finer toothed leaves without the foul smell or the glands. Leaf scars on Smooth Sumac practically circle the buds. There is no confusing this species if the red fruit is present.
Beech Bark Disease was first recorded in Michigan in 2000. The first records came from Luce County in the eastern Upper Peninsula and Mason County in the Lower Peninsula. It has since spread through the central and eastern Upper Peninsula and the northwestern Lower Peninsula. My photos came from Hartwick Pines State Park. It is only a matter of time before it reaches the American Beech (Fagus grandifolia) stands in southeastern Michigan. It could spread there from northern Michigan, southern Ontario, or eastern Ohio.
Beech Bark Disease consists of two components: a scale insect and a fungus. First, the non-native sap feeding scale insect (Cryptococcus fagisuga) infests the tree. These insects feed through tiny holes penetrating the bark. Fungi in the genus Nectria enter through these wounds and they kill the cambium layer. If it infests enough area, it can girdle and kill the tree.
Three species of fungi can cause Beech Bark Disease. Nectria galligena is native and caused little damage to American Beech until this scale insect was imported. N. faginata and N. ochroleuca are non-native. Sometimes more than one species of Nectria is present. Note: some researchers place these fungi in the genus Neonectria.
Closeups showing wooly white substance produced by the scale
The scale insects produce a wooly white substance. The insect shells seen in my photos are not from the scale insects but are from some other insect that was possibly feeding on the scale. Several Ladybug species feed on the scale however they cause little harm to the overall scale population. Fruiting bodies from the fungi are seldom seen, but its presence is recognized by a decline in the overall health of the tree.
This disease should be watched for and if found reported to the Department of Natural Resources, Forest Health Division.
American Chestnut (Castanea dentata) was once a common tree in southeastern Michigan. Charles Otis in his 1925 book, Michigan Trees, gives the distribution as: “South-eastern Michigan, as far north as St. Clair County. Abundant in eastern Monroe County and Wayne County.” This changed in the 1930s when the Chestnut Blight (Cryphonectria parasitica), a parasitic fungus from Asia, reached Michigan, killing most of our mature trees. I have seen a few fruiting native American Chestnuts; most of the trees are small stump re-sprouts that seldom, if ever, produce fruit. In the 1970s, I could still find rotting Chestnut logs on the forest floor in some Oakland County woods. Trees planted farther north in Benzie, Leelanau, and Missaukee Counties have largely escaped the blight.
American Chestnut bark and trees
A friend sent me photographs of a fruiting Chestnut tree he found in northern Oakland County that he thought was an American Chestnut. He is a great woody plant guy. I found the tree from his directions (a location I agreed not to share) and it is an American Chestnut.
Horse-chestnut leaves and fruitHorse-chestnut buds and nuts
Most reports of Chestnuts are the unrelated Eurasian tree, Horse-chestnut (Aesculus hippocastanum). This illustrates the danger of using only common names. I know someone who was gathering a bushel of Horse-chestnuts each year from a large tree in his yard and shipping them to Michigan State University. Finally, he received a letter politely explaining that they had a “sufficient supply of seeds” and needed no more. Horse-chestnut has opposite, palmately compound leaves. The stout twigs have large, red, sticky, buds. This species does not resemble the true Chestnut. It is the “spreading chestnut tree” in Henry Wadsworth Longfellow’s poem “The Village Blacksmith.”
American Beech leavesAmerican Beech pointed buds and leaves
American Beech (Fagus grandifolia) leaves with their parallel veins and coarse teeth resemble Chestnut leaves. Beech leaves are smaller than Chestnut leaves and have finer teeth. Bristles often tip the teeth on Chestnut. If you can study the tree and not just the leaves, American Beech has tight, gray bark and long pointed leaf buds.
Chinquapin Oak
Chinquapin Oak also called Yellow Chestnut Oak (Quercus muehlenbergii) resembles American Chestnut, but the lower surface of the leaf is pale-pubescent. The leaves are coarsely toothed and the teeth never have awls.
Chinese ChestnutChinese Chestnut
Chinese Chestnut (Castanea mollissima) is sometimes planted as a replacement for American Chestnut. It resists the Chestnut Blight. The undersides of its leaves are pubescent, and its buds are hairy. Hairs are also found on the spines of the nut coverings. Chinese Chestnut leaves are smaller than American Chestnut and have a squared off base with few teeth,
American Chestnut leavesAmerican Chestnut nut covers and nutsAmerican Chestnut twigs and nut spines
American Chestnut has the underside of the leaves smooth or with just a few hairs. The buds and nut spines are largely hairless. The leaves taper at both ends and are toothed to the leaf base with awl-tips. The leaves are larger than Chinese Chestnut. The American Chestnut Foundation has helpful hints for identifying American Chestnut.
Donald Peattie reminisces in his A Natural History of Trees: “from the upper slopes of Mount Mitchell, the great forest below waving with creamy white Chestnut blossoms in the crowns of the ancient trees, so that it looked like a sea with white combers plowing across its surface. Gone forever is that day;” I cannot imagine what that would look like.
At an event distributing white oak saplings for the bicentennial of Oakland County I was asked, “Are the large Tamaracks in Oakview Cemetery native?” Oakview is a century-old cemetery in Royal Oak. The back of the property was undeveloped woods when I was a boy. Tamaracks were harvested in Royal Oak township for the ship building industry in the late 1800s, but I did not know of any Tamaracks remaining in the city. Notes from the 1817 land survey seem to indicate that the cemetery land was always dry, but a swampy area was just to the southeast. Geological maps show a sandy beach ridge running across the property.
European Larch trees L Eastern Tamarack Oakview Cemetary R
I followed the directions and found the trees quickly by driving the center road to the west. Once I saw the shape of the trees, I knew they were European Larch (Larix decidua). This is also called European Tamarack. It is similar to our native Eastern Tamarack (Larix laricina). See my blog post.
European Larch L Eastern Tamarack REuropean Larch
Just like our native Tamarack, European Larch needles turn a bright yellow in the fall before they are shed for the winter. European Larch has bigger cones with 35-50 scales that have short hairs. Our native tamarack has less than 20 scales and they are hairless. European Larch needles normally are longer than 2.5 cm [1 inch]. They are shorter on our native Eastern Tamarack. The twigs on the European Larch are yellowish. Our Native Tamarack has brownish twigs that turn gray with age.
European Larch cones and needlesEastern Tamarack cones and needles
I walked around the cemetery looking at other trees. It has some large Black Oaks and nice White Pines. Just below the crest of the beach ridge I found an Eastern Tamarack with a trunk 2-feet in diameter. I think it was planted on the ridge because Eastern Tamarack does not grow on dry sandy sites.
It was interesting to walk the cemetery, looking at old trees. There are not too many sites where you can compare the two Tamarack species.
Balsam Fir (Abies
balsamea) is a common northern Michigan tree that I seldom see with cones. However,
two small Balsam Firs in our “yard” at The Cabin fruited this year. They are
approximately 15 feet tall. Part of my problem finding cones is that they form
in the upper branches and I do not climb trees. Another problem is the nature
of Fir cones. Their scales are deciduous so complete cones do not fall to the
ground but break into pieces. Small winged seeds disperse
on the wind. This leaves a woody axis resembling a bare branch sticking
straight up at a right angle to the branch.
Balsam Fir Cones L Cone scales RCone scales with seeds L Winged seeds R.
While out walking the next day I found the distinctive scales on the trail. I was in a dense grove of a dozen trees but could not spot the fertile Fir. Now that I recognize the scales I hope to spot more fertile trees. Barnes and Wagner in Michigan Trees state “the woody cone axis persistent on uppermost branches in winter.” Maybe I will find more fertile trees this winter. In an earlier blog post I talked about how to identify Balsam Fir, and to distinguish it from Hemlock and Spruces.
Seven native species and one commonly escaped species of maple
occur in Michigan. Maples have opposite leaves. Trees in Michigan with opposite
leaves are Maples, Ashes, Dogwood, Horse-chestnut, and Ohio Buckeye. I remember
“MAD Horse” to know the opposite
leaved trees.
Alternate OppositeIdentifying TermsAsh
Horse-chestnut and Ohio Buckeye have palmately compound leaves
(the leaflets radiate from a single point similarly to your fingers on your
palm). Dogwoods have simple leaves with entire margins (no teeth along the
edges of the leaves). Ashes are pinnately compound with 7 to 13 leaflets.
Box-elder is our only maple with compound leaves and it rarely has more than 5
leaflets. Once you know you have a maple this is how you identify the maples to
species:
Flowering DogwoodOhio Buckeye L Horse-chestnut R
Box-elder or Ash-leaved Maple or Manitoba Maple (Acer negundo) has compound leaves, course teeth on the leaflets, and a whitish bloom on the twig. Clusters of paired seeds hang on the tree in the summer and fall giving another method to distinguish this from the ashes.
Box-elderBox-elder leaf variations
Silver, Red, Mountain and Striped Maples all have the main leaf
sinuses acutely angled at the base. The other simple leaved species have leaf
sinuses that are rounded. This takes a little practice to discern but the
photos should help.
Red Maple L Silver Maple R
Silver Maple L
Silver Maple (Acer saccharinum) leaves are whitish-silver
beneath with coarse toothed leaf margins. It has five main lobes with the edges
of the middle lobe diverging. It is coarser toothed than the Red and Mountain
Maples and lacks teeth in the sinuses. The sinuses extend 2/3 of the way to the
midrib. It is one of our earliest flowering trees: flowering before the leaves
develop. Silver Maple flowers lack sepals and petals and have a hairy ovary.
Chew a twig if you are not sure it is Silver Maple. To me they have a foul
taste.
Silver MapleRed MapleRed Maple
Red Maple (Acer rubrum) leaves are whitish-silver beneath
with finely toothed leaf margins. It has three main leaf lobes with the edges
of the middle lobe converging. The sinuses extend 1/2 way to the midrib and are
finely toothed. The first-year twigs are normally red. It flowers when Silver
Maple flowers, also before the leaves develop. Red Maple flowers have sepals
and petals and a smooth ovary.
Mountain MapleMountain Maple
Mountain Maple (Acer spicatum) leaves are covered with
whitish downy hairs beneath. It is a small tree more common in northern
Michigan but I know one Oakland Co. stand. Its leaves resemble Red Maple but
are more finely toothed and not as deeply lobed. It flowers in the early summer
when its leaves are fully developed. The upright racemes of flowers or fruits
help to identify this maple.
Striped MapleStriped Maple
Striped Maple or Goosefoot Maple or Moosewood (Acer
pensylvanicum) is similar to Mountain Maple. Striped Maple has finer,
doubly serrate leaves, lacking hairs on
the lower surface. Doubly serrate means that the teeth have smaller teeth. The
lobes have tapering tips. Second year twigs have distinctive white stripes. It
flowers in the early summer when its leaves are fully developed. The drooping
racemes of flowers or fruits help to identify this maple.
Norway, Sugar, and Black Maples all have leaf sinuses that are
rounded at their base.
Norway MapleNorway MapleNorway Maple
Norway Maple (Acer platanoides) is native to Europe but is
now spreading from cultivation into wild areas in southern Michigan. Dark-green
leaves with narrow almost awl-like tips distinguish this from Sugar Maple.
Leaves are paler underneath than above with hairy tufts in the leaf axils. In
the summer its petiole emits a sticky, milky juice when broken. Fruits are
paired samaras that diverge 170 degrees. The seeds are flat, barely thicker
than the wings. Terminal buds are rounded not sharp as in Sugar Maple. Norway
Maple leaves stay green later in the season than Sugar Maples.
Sugar MapleSugar Maple
Sugar Maple or Hard Maple (Acer saccharum) is similar to
Norway Maple but with lighter green, five-lobed leaves. Its leaves are more or
less smooth underneath but sometimes it has hairs at the leaf base where the
veins join. In the summer its petiole emits a non-milky, clear juice when
broken. I often look for the sharp terminal bud to distinguish Sugar from
Norway Maple.
Black MapleBlack Maple
Black Maple (Acer nigrum) is a pragmatic species that
intergrades into Sugar Maple. Barnes and Wagner in their Michigan Trees accept
this species, Voss in his Michigan Flora treats it as a variety of the Sugar
Maple, and Reznicek on the Michigan Flora website accepts it with reservations.
The extreme forms are distinct. Black
Maple has three-lobed leaves with drooping leaf tips. They are pubescent
underneath and on the petioles. Leaf stipules are normally present. Twigs are
straw-colored. Black Maple is a tree of wet soil growing in river bottoms.
However, intermediates exist that resemble Sugar Maple but with pubescent
veins. They could be hybrids between Black and Sugar. It might be better to
treat them as one variable species. I’m content to know that I cannot name
every individual and call them Sugar / Black Maple.
Here is a link to my blog post on identifying maples using their seeds.
There is a citizen scientist project headed up by Steve Gougherty. Steve is a graduate student at the Finzi Lab at Boston University. He is studying Red Maples and needs volunteers to collect samples for him. He started the TASpeR (Traits Across Species’ Ranges) website. This site provides information on his study and a link to sign up if you want to participate. He asks for two collections: one of green leaves and one after the leaves have fallen. He is studying foliar nutrient resorption. His website explains what this means. Sign up if you want to collect for him.
In Michigan our broadleaved trees shed their leaves every autumn and most of our conifers hold their leaves (needles) for multiple years. All of our broadleaved trees are true flowering plants also known as angiosperms. Our conifers are non-flowering plants called gymnosperms. They have pollen cones and seed cones that technically are not flowers.
Tamarack trees before needle drop
Tamarack is our only native conifer that drops its needles for the winter. Our other conifers do not hold their needles forever but shed some each year, normally in autumn. White and Jack Pines hold needles for two years, Red Pines four to five years, White and Black Spruces, and Balsam Fir seven to ten years. Evergreens photosynthesize year round. Their needles have a waxy coating called the cuticle which slows down water loss. Evergreens are also less tasty to predators than broadleaved trees. Evergreens tend to have an upright growth making them less likely to get damaged by accumulating snow.
White Pine showing third year needles about to fall
Deciduous trees shed their leaves at the end of the growing season. This prevents water loss through the large surface area of the leaves. Deciduous trees catch little snow in the winter. In southern Michigan we had an early snow before the leaves dropped and many limbs were broken from the weight of the snow. Leaves on deciduous trees are often damaged during the growing season by insects, fungi, animals, or wind. This annual replacement refurbishes the leaves. Some writers suggest that the bare branches at flowering time allow for better pollination especially for wind-pollinated species.
When deciduous trees start losing their leaves they reabsorb some of the nutrients from their leaves. Chlorophyll, the green color in the leaves, is one of the first chemicals to be broken down and absorbed. This is why tree leaves turn colors in the fall. In Michigan each group of trees normally has a distinct color. Ashes tend to be red-purple, Oaks yellow-brown, Aspens yellow, Sugar Maples orange-red, Silver Maples yellow, Red Maples red, Sassafras orange, and Hickories yellow. Color varies from season to season and exceptions to these general rules are common. However, with a little practice it is possible to locate particular tree species by their color.
Thanks to my friend Judith who suggested this blog post.
A winter walk through a woods in Michigan will reveal deciduous trees holding their dried leaves from last fall. Marcescence is the technical term for plant parts that wither but do not fall off. It can refer to leaves, flowers, or fruit. In deciduous leaves an abscission layer forms at the base of the petiole (leaf stem). In most deciduous leaves the abscission layer hardens on the twig side in the fall, the leaves drop-off, and this layer protects the bud-scar on the twig. In marcescent leaves, the abscission layer does not function until buds break in the spring. Andrew Hipp at The Morton Arboretum explains this in greater detail.
Some species are more marcescent than others. Oaks, Beeches, Hornbeams, and Hop-hornbeams commonly hold their leaves. Younger trees exhibit marcesence more often than mature trees. Stress from drought or disease can cause marcescence in any deciduous species .
The color of the winter leaves is normally distinctive but hard to describe. With a little practice you can learn to identify these trees at a distance. Of course, looking at the shape of the leaf, winter bud, or the bark can confirm your identification.
American Beech leaves in winter
Marcescent leaves on American Beech (Fagus grandifolia) bleach from tan to a ghostly cream-color during the winter. Looking closely at a twig you will see long buds that confirm the identification.
Hop-Hornbeam leaves and winter bud
Hop-hornbeam (Ostrya virginiana) has winter leaves that tend to curl. Once again, with practice the color is distinctive. Blue-beech or Hornbeam (Carpinus caroliniana) is similar to Hop-hornbeam but with lighter brown leaves.
Blue-beech winter leaves
Oaks (Quercus spp.), especially the Black Oak group (subg. Erythrobalanus), tend to hold their leaves. Some years ago, when Dr. Warren Wagner was studying Shingle Oak (Quercus imbricaria) we learned to identify the species when we drove by. Shingle Oak leaves are tan or “potato-brown color.” Other oak species have a darker, reddish-brown color. Shingle Oak is Michigan’s only simple-leaved oak. Its leaves look more like bay leaves than what we in the north think a “typical” oak leaf should resemble.
Shingle Oak – L Pin Oak – R
It is fun to walk through a winter woodlot and identify the leaf-holding species. In Tenhave Woods, in Royal Oak, you can see where the ridges run through the woods by looking at the location of the Beech trees. Hornbeams ring the low swamp forest. Winter often is the best time to get an overview of an area when you can see farther and having the ability to identify some species from a distance is helpful.
Last Fall, my friend Trapper Dave contacted me and asked what was killing the Jack Pine (Pinus banksiana) in a Kirtland’s Warbler planting near his cabin in Oscoda County. This planting was the subject of an earlier blog post. Needles on branches and entire trees suddenly turned brown. We checked other plantings and found dead trees several other places in Oscoda, Crawford, and Montmorency counties. Several of these stands were two year old Kirtland’s Warbler plantings and we became concerned about the impact this die-off might have on this endangered bird.
Trapper Dave contacted the DNR and a helpful Forest Health Technician replied that, “We have had several reports from roughly a four county area of this type of mortality. The pictures you sent are consistent with other pictures we have received from this area… I’ll be sure to send you a some more information once we are able to make a diagnosis.”
Later we received a report from the Diagnostic Services at Michigan State University. They identified Sphaeropsis canker (Sphaeropsis sp. or spp) as the cause of the die-off. From the limited sample, submitted by the Forest Technician, they could not identify which species it was or even if more than one species is involved. The genus is poorly understood and probably has many undescribed species.
Jack Pine needles showing Sphaeropsis shoot blight
I looked up the fungus in Tree Maintenance (6th edition) by Pirone, Hartman, Sall, and Pirone. They list another newer generic name, Diplodia but use Sphaeropsis. They write that the fungus “overwinters in infected needles, twigs, and cones. In spring, the small fruiting bodies release egg-shaped, light brown spores… The fungus grows down through the needles and into the twigs, where it destroys tissues as far back as the first node.” (page 425).
Close-up of needle showing Sphaeropsis shoot blight spores
Several sources state that the spores overwinter in the cones but I could not find spores in the half-dozen cones I checked. The fungus kills the branches quickly. Die-off appeared over a two-week period but the trees must have been infected for most of the summer.
A USDA Northeastern Area Fact Sheet states, “Sphaeropsis shoot blight, formerly called Diplodia shoot blight, is worldwide in distribution and can infect many conifer hosts. Although many pine species are reported hosts, this disease causes severe damage only to trees that are predisposed by unfavorable environmental conditions. …Other predisposing environmental factors include poor site, drought, hail or snow damage, compacted soils, excessive shading, insect activity or other mechanical wounding. In the north-central United States, the most common hosts are Austrian, Scotch, mugo, red and jack pines grown in ornamental and windbreak plantings.”
We need to monitor the extent of the shoot blight damage in the Grayling area. It is a native fungus attacking a native tree that should have defense mechanisms. It was a dry year in the Grayling area so this may have made the trees more susceptible to infection. I am concerned that the USDA lists Jack Pine plantings, which of course is what we do for Kirtland’s Warbler, as being more susceptible to the infection. I did not find the fungus in the half dozen naturally occurring Jack Pine stands that I checked. If you find this fungus please report the location in the comments section of this blog post.
Copyright 2016 by Donald Drife
