Category Archives: Trees

What Made This Tree Fall?

Three Duquesne Light trucks at fallen oak on Bartlett Street, Schenley Park, 30 Sept 2018, 6:40pm (photo by Kate St. John)

Yesterday morning this oak was intact as we searched it for warblers in Schenley Park.  Last evening three Duquesne Light trucks were parked below it, fixing the wires it hit when a big chunk fell on Bartlett Street.

Here’s what broke (photo below). Most of the tree still stands but I wouldn’t be surprised if DPW chops it down now that it “misbehaved.”

Oak branch broke and fell on Bartlett Street, Schenley Park, 30 Sept 2018 (photo by Kate St. John)

This is not the only 100-year-old oak that’s fallen in the park in recent weeks.  This oak fell across the Falloon Trail in July …

Oak tree fallen across the Falloon Trail, 18 July 2018 (photo by Kate St. John)

… and this one fell last week at the edge of Overlook Drive.

Oak down on Overlook Drive, Schenley Park, 30 Sept 2018 (photo by Kate St. John)

None of the crashes were caused by strong wind. The trees just broke and fell.  The Fallon and Overlook trees had root rot, caused by Armillaria fungus. (See below for more on the Bartlett tree.)

You can see it inside this fallen trunk: black sheets of old Armillaria and white sheets of mycelium, the new growth, in the center.

Root rot inside fallen oak, black Armillaria rot and white mycelium (photo by Kate St. John)

If this stump was damp on a warm, very dark night (impossible in Schenley Park) the fungus would glow in the dark — a phenomenon called foxfire.

We usually don’t know that a tree is infected but the fungus will give us a hint this month.  Armillaria produces fruit in autumn that we call honey mushrooms.  (Here’s a USDA photo of one species, Armillaria tabescens.)

Armillaria tabescens at the base of a young oak (Theodor D. Leininger, USDA Forest Service, Bugwood.org)

If you find honey mushrooms at the base of a tree, that tree is infected.

Unfortunately there’s a lot of Armillaria in Schenley Park.  I’ll look for mushrooms this month to find out who’s in trouble.

NEWS about the Bartlett tree: The branch that fell on Bartlett Street was hollow — probably not Armillaria but it was bad nonetheless.  Here’s a photo of the thickest part of the branch after it was chopped up.

Inside of hollow branch that fell on Bartlett Street, 30 Sept 2018 (photo by Kate St. John)

p.s.  Yes there are mushrooms in the city parks but it’s illegal to harvest them, even for personal use.

(Schenley Park tree photos by Kate St. John. mushroom photo by Theodor D. Leininger, USDA Forest Service, Bugwood.org)

Cucumber Tree

Magnolia cucumber fruits, green and ripening (photos from Wikimedia Commons)

There’s a cucumber in the woods but you won’t see it until it falls.

Native to the Appalachians, Allegheny and Cumberland Plateaus, the cucumber magnolia (Magnolia acuminata) produces an unusual fruit that starts out green, ripens to dark pink, then its red-orange seeds pop out. (The one on the right isn’t fully ripe yet.)

When the fruit falls in autumn it’s quickly gathered by squirrels and chipmunks.  You’ll find the ones they miss on the forest floor.

Learn what it looks like in this Throw Back Thursday article: Cucumber of The Woods.

(photos from Wikimedia Commons, click the links to see the originals: unripe green cucumbertree fruit and ripening fruit)

Ooops! It Fell

Spray of white oak leaves found on the ground, Sept 2018 (Kate St. John)

In September I often find sprays of oak leaves littering the woodland trails. I used to think they fell in windstorms but I’ve discovered a more common reason. In autumn it’s squirrels at work.

Gray squirrel (photo by Chiswick Chap via Wikimedia Commons)

Gray squirrels build leaf nests high in the trees for shelter in winter, nests for their young, and for sleeping at night.  The outer layer is composed of leaves and twigs that make a water resistant blob about the size of a beach ball. The inside is lined with moss, grass, shredded bark and other soft vegetation. The entrance faces the trunk. 

Squirrel nests can be as much as 70 feet off the ground. Here’s what one looks like. 

Gray squirrel nest (photo by Marcy Cunkelman)
Gray squirrel nest (photo by Marcy Cunkelman)

To gather building materials, the squirrel gnaws near the branch tip — often an oak — until the spray of leaves comes loose.  If he isn’t careful to hold the twig, it falls. Oh well. The squirrel gnaws another one.  

You can tell when a spray of leaves is a squirrel’s handiwork.  The tip of the twig looks chiseled. Teeth made this mark!

Tip of a white oak twig chiseled by a squirrel (photo by Kate St. John)

Last week I found many leafy twigs on the trails in Pittsburgh.  After four days of cold rain the squirrels were making nest repairs.

As winter approaches you’ll find them, too. The squirrels are fortifying their nests and they don’t have much time. The leaves will be gone in November.

(photos by Kate St. John, Marcy Cunkelman and from Wikimedia Commons; caption has a link to the original)

Webs In The Trees

Fall webworms (photo by Ronald F. Billings, Texas A&M Forest Service , Bugwood.org)

Have you seen big webs in the trees lately?  If you haven’t, you will soon.

These are the communal homes of fall webworm caterpillars, the larvae of the fall webworm moth (Hyphantria cunea).

Each colony hatched from an inconspicuous egg mass, then the caterpillars built a web to protect themselves from predators. As they grow they expand their web.

Because this is the end of the growing season, the webs usually don’t hurt the trees. Meanwhile the caterpillars are tasty treats for migrating songbirds.

See the handsome adult moth and learn more about the caterpillars in this 2011 article: Coming Soon To A Tree Near You

(photo by Ronald F. Billings, Texas A&M Forest Service , Bugwood.org)

Eat Pawpaws in September

Pawpaw fruits (photo by Rebekah D. Wallace, University of Georgia, Bugwood.org)

Have you ever eaten North America’s largest native fruit?  Chances are you haven’t.  In fact, most people don’t know what it is.

The pawpaw (Asimina triloba) grows on small mid-story trees from southern Pennsylvania to Alabama to eastern Kansas.

Pawpaw range map from Wikimedia Commons

The fruit is sweet like mango with a creamy texture like ripe banana. Despite its sweet addictive flavor, pawpaws aren’t in widespread commercial production because the fruit is so ephemeral. Some would say it’s finicky.

  • Pawpaws ripen only once a year — in September.
  • They ripen only on the tree. They can’t be picked in advance.
  • The fruit bruises so easily it has to be shipped in expensive padded packaging. 
Pawpaw fruit (photo from Wikimedia Commons)

In the old days, people would gather fallen pawpaws as they walked in the woods in September. This practice eventually disappeared and most people forgot about the fruit until a dedicated group of pawpaw enthusiasts and Andrew Moore’s 2015 book, Pawpaw, made it better known.

Want to taste a pawpaw?  The best place to do it is at a pawpaw festival.  Eat them raw or in ice cream, pies, popsicles, and even beer!

There are three pawpaw festivals within driving distance of Pittsburgh.

Before you go, this 2014 video from Connecticut shows what pawpaws look like and how to eat them.

p.s. Don’t eat the seeds. They are emetic.

(photo credits: pawpaws on tree by Rebekah D. Wallace, University of Georgia, Bugwood.org. Range map and sliced fruit from Wikimedia Commons. Click on the captions to see the originals)

Oak Apple Gall

Oak apple gall, August 2018, Pittsburgh, PA (photo by Dianne Machesney)

I’ve never sliced open an oak apple gall but the North Park walkers did while Dianne Machesney took photographs.

Inside the oak apple gall, August 2018 (photo by Dianne Machesney)

It was red and juicy inside.  Hmmm!

We don’t know which bug made this gall and the bug died in the slicing so …

Can any of you identify this gall and the insect that made it? It was found in North Park, Allegheny County, Pennsylvania in mid August.

(photos by Dianne Machesney)

Papery Husks

American hazelnuts, Schenley Park, July 2018 (photo by Kate St. John)
American hazelnuts, Schenley Park, July 2018 (photo by Kate St. John)

In late July, you may find nuts wrapped in papery green husks.

They’re American hazelnuts, Corylus americana, so closely related to the beaked hazel-nut Corylus cornuta that the two species can hybridize.  The nut wrappers tell them apart.

The husks on C. americana’s nuts are two leaf-like bracts with ragged tips. This photo by Paul Wray at forestryimages.org shows hairy leaf bracts and an unwrapped nut.

American hazel nut (photo by Paul Wray, Iowa State University via Bugwood.org, Creative Commons license)
American hazel nut (photo by Paul Wray, Iowa State University via Bugwood.org, Creative Commons license)

Beaked hazel-nut (C. cornuta) husks are so long and thin that they look like beaks, as seen in this photo from forestryimages.org.

Fruits of beaked hazelnut ((Caleb Slemmons, National Ecological Observatory Network, Bugwood.org, Creative Commons Attribution-Noncommercial 3.0 License))
Fruits of beaked hazelnut (Caleb Slemmons, National Ecological Observatory Network, Bugwood.org, Creative Commons Attribution-Noncommercial 3.0 License))

The nuts I found in Schenley Park don’t have long beaks but they aren’t quite the same as the C. americana photo above.

I wonder if they’re hybrids.

 

(two photos by Kate St. John. photo number 5556599 by Caleb Slemmons, National Ecological Observatory Network, at Bugwood.org)

Balsam Blue

Balsam cones, La Manche Trail, Newfoundland, July 2018 (photo by Kate St. John)
Balsam cones, La Manche Trail, Newfoundland, July 2018 (photo by Kate St. John)

Did you know that the immature cones on balsam firs are gray-blue?  I didn’t because …

I see balsam trees every year in Maine but I’m only there in September when the cones are ripe and brown and about to disintegrate to release their seeds.

Where I live in western Pennsylvania there are no balsam firs (range map below) but eastern hemlocks are common. Hemlocks have some traits that are similar to balsam firs, so …

Balsam fir range map (image from Wikimedia Commons)
Balsam fir range map (image from Wikimedia Commons)

… when I saw balsam firs (Abies balsamea) in Newfoundland I misidentified them at first.  🙁

The balsam’s lower/newer twigs have flat needles on flat-looking branches.  Eastern hemlocks do, too, so I called this a hemlock.  (wrong!)

Balsam fir, symmetrical flat lower branch (photo from Wikimedia Commons)
Balsam fir, symmetrical flat lower branch (photo from Wikimedia Commons)

Balsam needles have two white stripes on the underside.  So do eastern hemlocks so I said “hemlock” again. (wrong!)

However, the needles curled on the higher branches.  Hemlock needles never do that.

Morning dew on balsam fir needles (photo from Wikimedia Commons)
Morning dew on balsam fir needles (photo from Wikimedia Commons)

In the end, the cones are the easiest way to identify balsam firs. The cones stand straight up and in summer they’re balsam blue.

 

p.s. Here’s a website that describes how to identify pines, spruces, and firs: Conifer Confusion: An Identification Guide for Pine, Spruce and Fir Trees.  I wish it said more about hemlocks!

(balsam cone photo by Kate St. John. All other photos from Wikimedia Commons; click on the images to see the originals)

Tamarack Rose

Tamarack cone in Newfoundland, July 2018 (photo by Kate St. John)
Tamarack cone in Newfoundland, July 2018 (photo by Kate St. John)

This month in Newfoundland I found a rose on the tamarack.

Tamaracks (Larix laricina) are North American larches whose name means “wood is good for fence posts” in Algonquin.

The “roses” are their immature cones. In summer the needles are green and the cones are red.

Tamarack branch with cones, Newfoundland, July 2018 (photo by Kate St. John)
Tamarack branch with cones, Newfoundland, July 2018 (photo by Kate St. John)

In autumn the needles turn yellow and fall off the tree.

Tamarack in autumn (photo from Wikimedia Commons)
Tamarack in autumn (photo from Wikimedia Commons)

And the cones turn brown and dry out.  They persist on the tree all winter and are still present when the needles grow again in the spring.

Mature tamarack cones in spring with young foliage (photo from Wikimedia Commons)
Mature tamarack cones in spring with young foliage (photo from Wikimedia Commons)

You have to look in the summer to see a tamarack rose.

 

(tamarack immature cone photos by Kate St. John. Yellow tamarack and mature cones photos from Wikimedia Commons; click on the images to see the original)