Which trees keep their dried leaves throughout the winter?

Fagus grandifolia

American Beech in winter

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.

Fagus grandifolia

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.

Ostrya virginiana

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.

Carpinus caroliniana

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.

Copyright 2017 by Donald Drife

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What Are the Yellow Balls on the Jack Pine?

Peridermium harknessii

Pine-Pine Galls sporing on Jack Pine

Last summer I was asked by a friend what the yellow balls infesting his Jack Pines (Pinus banksiana) were. They were obviously some kind of gall forming rust and were quite striking even from a distance.

Peridermium harknessii

Pine-Pine Galls sporing, note spores on needles and bark below left hand gall.

The rust was Peridermium harknessii and it goes by a variety of common names such as Western Gall Rust, Pine-Pine Gall Rust, and Rust Pine Yellow Disease. It has been placed by some taxonomists into the genus Endocronartium.

Peridermium harknessii

Pine-Pine Galls are inconspicuous when not sporing.

Peridermium harknessii

The bright yellow spores are unmistakable.

It is common in the Jack Pine Plains near Grayling. The yellow spores appear in late May or June from the semi-spherical galls. A gall will produce spores for several years. The woody gall remains on the branch or trunk throughout the year and will persist after the branch dies. It is not a serious pest in Michigan and the hosts are killed only if the rust infects the main trunk of small trees. Infected mature trees often only lose a few branches.

Peridermium harknessii

The remains of a Pine-Pine Gall persist long after the branch dies.

Unlike many rusts, Pine-Pine Gall Rust has a single host cycle. Meaning that it spores and directly infects other pines. I have only seen this species, in Michigan, on Jack Pine but it has been reported on Scots Pine (Pinus sylvestris). My blog post regarding Poison Ivy Rust presents further details on the life cycles of various rusts.

Look for this colorful species in late spring.
Copyright 2017 by Donald Drife

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Brown Marmorated Stink Bug

I recently found a stink bug in my kitchen. It was a Brown Marmorated Stink Bug (Halyomorpha halys). This invasive insect is native to Japan, Korea and China. The first North America record was from Allentown, Pennsylvania in 1998 and it reached Michigan in 2011.

Halyomorpha halys

Brown Marmorated Stink Bug

The adults overwinter in houses, barns, garages, and outbuildings. Adults are 12-16mm [1/2-5/8 inch] long and shaped like a shield. Their antennae are dark with light bands. Light spots are also found on the edges of their bodies. This is the only species of stink bug commonly found inside a house during our Michigan winter. It can occur by the hundreds in some homes.

Halyomorpha halys

Brown Marmorated Stink Bug

Brown Marmorated Stink Bugs will not bite humans. They can be a major pest on fruit trees and damage the leaves and fruit of apples, pears, peaches, cherries, corn, tomatoes, peppers, soybeans, and others. Luckily they only raise one brood in Michigan.
Copyright 2017 by Donald Drife

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What is Killing the Jack Pine?

Sphaeropsis shoot blight

Sphaeropsis shoot blight

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.

Sphaeropsis shoot blight

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).

Sphaeropsis shoot blight

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

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Eastern Ironclad Beetle (Phellopsis obcordata)

Phellopsis obcordata

Eastern Ironclad Beetle on shelf fungus

Last August, I found a beetle, resembling a woodchip, sitting on a shelf fungus along the old growth trail in Hartwick Pines State Park. On this field trip I was looking at fungi with a friend or I probably would have overlooked this well camouflaged beetle. It was an Eastern Ironclad Beetle (Phellopsis obcordata). According to bugguide.net they eat “fungi associated with decaying trees in old growth boreal forests.” I love when a beetle reads and follows the rules. The larva burrows inside the fungus eating pathways. The adults feed on the surface of the fungus. I have visited Hartwick Pines several times a year over the last four decades and I still find new things to see. You never know what you are going to find.

Phellopsis obcordata

Eastern Ironclad Beetle

 

Copyright 2016 by Donald Drife

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Cottonwood Gall Aphids (Pemphigus populitranversus)

Pemphigus popilitranversus


Cottonwood Gall

While I was raking leaves off our small “lawn,” my wife (knowing full well the answer would be yes) asked me if I wanted to see a leaf gall. It was formed on the petiole of an Eastern Cottonwood (Populus deltoides). I checked bugguide.net and identified that a Cottonwood Gall Aphid caused the gall.  Poplar Petiole Gall Aphid is another common name for this species.

Pemphigus popilitranversus

Cottonwood Gall                  Left hand gall showing transverse split

It is a hollow gall, not quite round, with a transverse split. It occurs along the petiole (the stem of a leaf) just below the blade. I cut a few open and found a waxy substance but no insects. They might have exited through the slit. I opened one more and found the adult aphid.

Pemphigus popilitranversus

Interior of Cottonwood Gall    L – shed skin                 R – adult winged aphid

I Googled the scientific name and the phrase “life cycle” and found Roberta Gibson’s informative and fun blog “Growing with Science (The Poplar Petiole Gall Aphid was the “Bug of the Week” in May of 2015.) She explains the aphid’s life cycle. Aphids seldom have straight forward life cycles. They over winter as eggs on Cottonwood twigs. They hatch in the spring and feed on the leaf petioles, causing the plant to produce the gall. Then the insect moves inside. It becomes a winged adult and exits through the slot in the gall’s side. They complete their life cycle on the roots of cabbage, turnips, or another member of the mustard family (Brassicaceae). Another common name is Cabbage Root Aphid. The aphids complete their life cycle by flying back to Cottonwoods and depositing eggs on the twigs or bark.

This is a great time of year to look for galls. Get outside and enjoy Nature. Also, check out Roberta’s blog and website. Even though she is based out of Arizona many things she writes about occur in Michigan.
Copyright 2016 by Donald Drife

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Don’t Touch That Beetle: Oil Beetle (Meloe sp.)

meloe-sp-oil-beetle-1During a recent work session at the Royal Oak Arboretum one of the Boy Scouts found a large purplish-black beetle. It was part of the Blister Beetle group called an Oil Beetle (Meloe sp.). They exude an yellowish oily substance from the base of their legs that forms blisters if it contacts human skin. They placed the beetle in a large plastic cup and the cup’s bottom was spotted with oily liquid when I first saw it.

This genus consists of six species in the Northeastern United States. I am not sure which species this one is. I am happy to know the genus of an insect.

Meloe sp.

Female Oil Beetle

The females are about twice the size of the males. This female was 40mm [1.5 inches] long and seemed sluggish. They overwinter as eggs and perhaps she had laid her eggs and was reaching the end of her life. This is a flightless, parasitic beetle. The eggs hatch in the late spring and the larva are described as alligator-like. Climbing onto a flower they wait for one of the solitary bees to land and quickly latch on to its back. The Oil Beetle larva rides the bee back to its nest and feeds on the developing bee larva and possibly some of the pollen in the nest. It then pupates and emerges in the fall to mate and lay its eggs.

It is fun to find a new insect in an area that I visit often. You never know what you are going to see when you just get out and look.
Copyright 2016 by Donald Drife

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A Parasitic Yellow Jacket

yellowjacket-nest

Yellow Jacket nest in old camper shell

Last summer I killed a Yellow Jacket nest that was constructed in an old camper shell at our cabin. Normally I coexist with the wildlife around me but I had a visitor who was allergic to wasp stings.

Dolichovespula arenaria

Aerial Yellow Jacket closeups

The workers were all Aerial Yellow Jackets (Dolichovespula arenaria). This is one of our native species. The yellow banding pattern on the abdomen is distinctive with a black “V” in the middle of the relatively wide yellow band. The face is almost solid yellow. The Canadian Journal of Arthropod Identification has a great website for wasp identification.

Dolichovespula arctica

Parasitic Yellow Jacket

I also found Yellow Jackets that were mainly black and white. These were Parasitic Yellow Jackets  (Dolichovespula arctica). This is the only parasitic species in the genus found in eastern North America. It also goes by the name of Dolichovespula adulterina.

Dolichovespula arctica, Dolichovespula arenaria

Parasitic Yellow Jacket – L
Aerial Yellow Jacket – R

D. adulterina is a broader classification and includes D. arctica. Whichever name you use there is still only a single parasitic Yellow Jacket species in Michigan.

Parasitic Yellow Jackets reproduce only in Aerial Yellow Jacket nests. A Parasitic Yellow Jacket queen invades an established Aerial Yellow Jacket nest. It either kills the Aerial Yellow Jacket queen immediately or coexists for a time with her and then kills her. Aerial Yellow Jacket workers raise the parasites’ young.  The parasite produces only males (drones) and queens who eventually take control of the nest. Each queen, once they mate, overwinters outside of the nest and then repeats the same process the following year.

I intend to look at Yellow Jackets more closely and hope to find a parasitized nest for further study.
Copyright 2016 by Donald Drife

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Review: “Michigan Shrubs & Vines”

The University of Michigan Press recently released Michigan Shrubs & Vines: A Guide to Species of the Great Lakes Region by Burton Barnes, Christopher Dick, and Melanie Gunn. This is a companion volume to Michigan Trees by Burton Barnes and Warren Wagner.

Species accounts are similar to the ones in Michigan Trees. Two pages for each species with a page describing size and form, bark, leaves, stems-twigs, winter buds, flowers, fruit and distribution. The section on site-habitat shows that the authors know these plants in the field. A notes section contains interesting tidbits that might include: growth habits, origin of common and scientific names, world distribution, or uses by Native Americans. A second page shows line drawings of the shrub and its key characters. I applaud the authors decision to use drawings instead of photographs. The selected drawings show the key characters and are excellent. Not every shrub is treated at this level. Some are only mentioned under the heading similar species.

From the species accounts I learned that Leatherleaf (Chamaedaphne calyculata) occurs in bogs in Japan. That Bearberry (Arctostaphylos uva-ursi) seeds “may remain viable in the soil for decades.” Also, that there are 58,000 Bearberry seeds to the pound. Wintergreen (Gaultheria procumbens) contains “methyl salicylate, closely related to the main ingredient in aspirin.” Leatherwood’s (Dirca palustris) fruit is correctly described as “pale green to yellowish-green when ripe.” Many guidebooks get this wrong stating it is purple or dark red which the fruit becomes if dried or rotting.

Michigan Shrubs and Vines contains a set of workable keys (and a section on how to use them including line drawings of many of the plant parts). The keys stress vegetative characters and allow identification without flowers and most of the time without fruit. I ran a dozen species through the keys and they worked flawlessly.

The final section of the book is headed “Ecology of Shrubs and Vines.” It distills some of Burt Barnes’ insights regarding ecology in a manner that laypersons will understand. This section alone is worth the price of the book. Shrub reproduction strategies, climate change, specific site factors, and Michigan’s four regional landscape ecosystems are among the topics discussed.

This book will allow you to identify Michigan’s shrubs and vines and then place them into the bigger ecological picture. It can be ordered from the University of Michigan Press and should be in the library of every naturalist in Michigan.

 
Copyright 2016 by Donald Drife

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Broad-leaved Helleborine’s Look-a-likes

Coeloglossum viride

Long-bracted Orchid L & C                                                       Yellow Lady-slipper R (Note hairs)

Many people have posted comments on an earlier blog post about Broad-leaved Helleborine (Epipactis helleborine). There is a lot of confusion regarding the identification of this species. I recently saw a photograph of this orchid identified as Spotted Coral-root  (Corallorhiza maculata). Broad-leaved Helleborine has several color forms and some of the field guides do not account for the variations.

Epipactis helleborine

Close-up of Epipactis flower showing distinctive orchid flower structures

If you have a plant in flower you can recognize it as an orchid because it has three sepals and three petals with one of the petals modified into a lip. The reproductive  organs are fused into a column. The leaves are parallel veined. (Note: Sepals are the outer covering of a flower bud. Petals are inside of the bud.)

Broad-leaved Helleborine’s flowers are about 15mm (5/8 inches) across and the lip is turned in at the tip.

Epipactis helleborine

Smooth leaves and stems of Broad-leaved Helleborine

When not flowering Broad-leaved Helleborine is commonly mistaken for one of the lady-slippers but its leaves and stem are smooth. Lady-slippers (Cypripedium spp.) have hairy leaves and stems. Helleborine normally has more leaves than a lady-slipper.

Long-bracted Orchid (Coeloglossum viride) has smaller flowers with notched lips and is not as coarse a plant as hellebore. It grows in natural areas and I have never seen it invading a garden.

Epipactis helleborine

Root of Broad-leaved Helleborine showing growth bud and side view of flower

While this is not a gardening blog many people ask about controlling this species. The only way I know is to try to dig out the plant. If you leave any of the fleshy root behind it will come back.  Note the growth bud for next year’s plant in the photo. Most orchid species have fleshy roots so please make sure you have the plant correctly identified before you dig. My earlier blog post showed this species growing with domestic Viburnum and, in spite of repeated digging, that colony is still growing. Plants appeared in my wildflower garden, but died out without any interference from me.

Broad-leaved Helleborine is probably growing in every county in the state. Learn the plant when it is flowering so you can identify it later in the year.
Copyright 2016 by Donald Drife

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