Category Archives: Trees

When Will Most Of The Trees Be Bare?

Leafless bur oak, Schenley Park, 4 Nov 2011 (photo by Kate St. John)

Every year I record the date when most of the trees are bare on my favorite hillside in Schenley Park — the hill at the end of the Greenfield Bridge.

In 2008 the leaves were gone by 2 November.  In 2012 Hurricane Sandy stripped them from the trees by 4 November.

Last year the changes happened much later. In 2017, the leaves were still green in late October and more than half were still on the trees on 27 November.  Here’s a 2017 slideshow of autumn trees on that hillside.

  • 26 October 2017: Lots of green at the end of October 2017.

This year is similar to last so I wonder … When will most of the trees be bare?  November 15?  20?  30? Later?

Let me know how the trees look where you live and vote for the date “When Most of the Trees Will Be Bare” by leaving a comment below.

HINT!  Two factors that affect leaf loss on this hillside:  (1) More than half of the trees are oaks; oaks drop their leaves later than maples.  (2) This city location is warmer than surrounding counties.

(photo by Kate St. John)

Stinky Fruit

Ginkgo tree with fruit, October in Schenley Park (photo by Kate St. John)

It’s time to tiptoe on the sidewalk at Flagstaff Hill.  The female ginkgo trees are dropping their smelly fruit on Schenley Drive. 

Ginkgo fruit on the sidewalk at Schenley Park (photo by Kate St. John)

Ginkgo fruit smells like stinky feet or vomit but the nuts inside are edible.

On Throw Back Thursday, learn about ginkgos in this 2011 article: Stinkbomb Tree.

(photos by Kate St. John)

Fall Foliage: When?

Moraine State Park, 15 Oct 2017 (photo by Kate St. John)

Summer ended on Friday morning. Brrrr! Now that it’s cold, it’s time for colorful fall foliage, right?

Some reports say western Pennsylvania won’t have pretty leaves this fall, others say we will.  One thing is certain, though. The leaves stayed green longer than usual.

Twenty years ago our fall foliage reached its peak around October 15 but today — only one day before the 15th — the leaves have just begun to change.  We had the same situation last year as shown in my photo taken at Moraine State Park on 15 October 2017.

Delayed timing makes it hard to know when fall color will reach its peak but the Pennsylvania Bureau of Forestry (DCNR) is here to help.  Check out their Fall Foliage Guide complete with an interactive map and weekly reports.  The October 11-17, 2018 forecast map is shown below (yellow means “approaching best color”). Click here or on the caption to see the full report.

screenshot of Pennsylvania Fall Foliage Report, Oct 11-17 2018, by PA DCNR

Don’t worry if you haven’t gone “leaf peeping” yet in western Pennsylvania.  You still have time to see fall colors this month.

(photo by Kate St. John, Screenshot from the Pennsylvania Fall Foliage Report, October 11-18, 2018, PA DCNR; click on the caption to see the original)

Un-Confusing Conifers

Eastern hemlock cones and foliage in Kentucky (photo from Wikimedia Commons)

I’m pretty good at identifying western Pennsylvania’s deciduous trees because I live with them, but evergreens aren’t common here and they confuse me.

After I flunked the spruce-fir-hemlock test in Newfoundland in July I vowed to learn from that experience and do better last month in Maine.  I updated my conifer “cheat sheet” and memorized the difference between balsam firs and hemlocks.

Conifers are still confusing but I’m doing better.  I got a B- in Maine.

How do you tell the difference between pines, spruces, firs and hemlocks?
Learn from my conifer cheat sheet: In A Coniferous State.

 (photo from Wikimedia Commons; click on the caption to see the original)

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,

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,

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 ,

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 ,

Eat Pawpaws in September

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

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, Range map and sliced fruit from Wikimedia Commons. Click on the captions to see the originals)