Monthly Archives: December 2013

Balsam Fir and Hemlock in Michigan

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Balsam Fir and Spruce Needles and Branchlets

Balsam Fir and Spruce Needles and Branchlets

Balsam Fir, (Abies balsamea) is a common conifer in northern Michigan. It often grows with Aspen (Populus grandidentata & P. tremuloides), Jack Pine (Pinus banksiana), or Paper Birch (Betula papyrifera). It is also found in White Cedar (Thuja) swamps and bogs. Often the needles form flat branchlets but the needles can encircle a branch, resembling a spruce (Picea) branchlet. When I began to look for spruce trees to photograph I was surprised to find that many of the stands I thought were spruce actually were Balsam Fir with their needles encircling the twigs. Spruces have square needle cross-sections and Balsam Firs have rectangular cross-sections. The needle scar, that is the mark left on the twigs when the needle falls off, is round on the Balsam Fir. Its needles fall and leave a clean branch. Spruces leave rough projections along the branchlets after the needles fall. Balsam Firs tend to hold their dead needles on older branches and spruces shed their needles. Balsam Fir has distinctive pitch filled pockets under the surface of its bark.

Abies balsamea Branchlet and Bark

Balsam Fir Branchlet and Bark

Abies balsamea Balsam Fir Needles

Balsam Fir Needles

Although I spend much of my field time in the range of Balsam Fir, I seldom see it producing cones. Perhaps they are produced at the tops of tall firs and I miss them. The cones fall apart, dehisce is the technical term, while still attached to the branches, so no cones fall to the forest floor. I often see seedling Balsam Firs so they must be producing cones.

Tsuga canadensis Branchlet Stomata Cones

Eastern Hemlock Branchlet, Stomata, and Cones

Eastern Hemlock (Tsuga canadensis) is common north of Bay City and rarer in southern Michigan where it will grow in a protected hollow or ravine. In the north, it will grow with hardwood trees, White Pine, or in pure stands. Hartwick Pines State Park has an elevated, barrier free, “treetop” walkway leading into its Forest Center. The walkway leads through a nice Hemlock and American Beech (Fagus grandifolia) woods. I enjoy walking through the treetops and peering into the canopy. I photographed the Hemlock cones from this platform.

The needles are short, normally less than 13mm (1/2 inch), blunt, with a few teeth toward the tip. They are dark green above and have a white stripe on the lower surface. The white stripe is actually composed of minute openings in the leaf called stomata. These openings allow the plant to “breath.” Hemlocks also have needles that lay on the twig, with their lower surface pointing up. The needles appear to occur in flattened clusters but actually are produced from around the twig. The leaves bend, giving the branch its characteristic flattened look.

Copyright 2013 by Donald Drife

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Viburnum Leafhopper (Enchenopa viburni)

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Enchenopa viburni Viburnum Leafhopper

Viburnum Leafhopper adult

I found this thorn mimic leafhopper last September on my Korean Spice Viburnum (Viburnum carlesii). To my eye, it did not blend in at all on this thornless shrub. The white masses are its eggs. This species was first named as a scale insect from a mistaken idea that these were insects and not eggs. After the mistake was noticed, the name was transferred to this genus.

When I found the eggs last September they were white and sticky. It is now December and the eggs are still white and sticky even on days when it is 10 degrees F. Perhaps this stickiness discourages birds from eating the eggs. I have seen Black-capped Chickadees in this shrub and they don’t seem to bother the eggs. The egg masses now have pieces of leaves and other dirt adhering to their surface but the egg masses themselves are still white and easy to notice. I expected them to darken with age so they would blend into the viburnum twigs better.

Enchenopa viburni eggs L-September R-December

Viburnum Leafhopper eggs L-September R-December

I know as a gardener I should destroy the egg masses, but I have never observed this species before and the egg masses are few in number. I want to study and photograph the nymph stage. I will monitor the insects in the spring to insure they are not serious garden pests.
Copyright 2013 by Donald Drife

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Poison Ivy Rust (Pileolaria brevipes) in Michigan

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Pileolaria brevipesToxicodendron radicans

Poison Ivy Rust

When I found this growth on a poison ivy vine in Tenhave Woods, Royal Oak, Michigan, I did not know if it was an insect gall, a fungus growth, or a rust. Because it was growing on Poison Ivy (Toxicodendron radicans sensu stricto) , I did not closely examine it. I searched the internet for “rust Toxicodendron radicans,” “rust Rhus radicans,”  and “galls” using both names with no luck. I studied the growths during the remainder of the summer and I was fairly certain that it was a rust.

I recently revisited the photos. Winter months are spent sorting and identifying photos. After searching the Internet for “rust poison ivy,” I found what looked like my poison ivy rust on Iowa State University’s Ada Herbarium website. It was under the name Pileolaria brevipes. This name lead me to an article by David Senchina titled “Fungal and animal associates of Toxicodendron spp. (Anacardiaceae) in North America” with photographs of my poison ivy rust.

Poison IvyPileolaria brevipesToxicodendron radicans Flowers Rust on flowering Poison Ivy

Poison Ivy Rust on flowering Poison Ivy

Rusts are a small group of parasitic fungi consisting of approximately 7000 species worldwide. Somewhere around 175 species occur in Michigan. Rusts are so-named because their spores are often orange or reddish-brown. They can cause severe damage to important agricultural and timber crops.

Rust fungi have fascinating and complex lifecycles. They can have up to six different spore states during their lifecycle and may need two distinct host plants during their lifecycle (heteroecious) or a single species (autoecious). A rust species usually grows on a specific host species or group of species.

Here is a simplified Wheat Rust lifecycle. It is a heteroecious species with Wheat and Barberry serving as hosts. Wheat Rust over-winters in the soil as a thick-walled spore. They germinate in the spring and produce other spores of two strains (or sexes) that are carried by the wind to the upper surface of Barberry leaves. These grow and produce another type of spore that infects the lower surface of the leaf. From this growth, spores are produced that the wind carries to Wheat. When the rust grows on its Wheat host it produces spores that can directly infect other Wheat plants and then in the fall it produces the over-wintering spores. For a detailed life-cycle of the Wheat Rust and more information on rusts see the University of Hawaii’s Botany Department website.

Poison Ivy Rust’s lifecycle is simpler having just three spore types and a single host plant. It is widespread across most of North America.

There is no popular field guide for Michigan’s rust species. George Cummins and Yasuyuki Hiratsuka produced an Illustrated Genera of Rust Fungi allowing the identification of rust to genus using microscopic characters. My research for this blog has taught me that I see more rust species than I have previously noticed.
Copyright 2013 by Donald Drife

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