Category Archives: Trees

Seen This Week

Sunrise, 11 Jan 2023 (photo by Kate St. John)

14 January 2023

The sunrise was gorgeous and cold last Wednesday when a group of us decided to walk at Jennings in Butler County. We saw few birds but there were ice heaves, buttress roots on an elm, and the seeds of old man’s beard (Clematis drummondii).

Ice heave at Jennings, Butler County 11 Jan 2023 (photo by Kate St. John)
Elm tree with buttress roots, Jennings, Butler County, 11 Jan 2023 (photo by Kate St. John)

When old man’s beard is in bloom it’s called virgin’s bower, transforming it from a young woman to an old man in a matter of months.

Seeds of Virgin’s bower, a.k.a. Old man’s beard, Jennings, Butler County, 11 Jan 2023 (photo by Kate St. John)

My friends who live north of the city have not seen many dark-eyed juncos at their feeders this winter, but juncos are definitely present at the Frick Park Environmental Education Center. Charity Kheshgi posted photos of our recent trip to Frick.

(bird photos by Charity Kheshgi embedded from Instagram, all other photos by Kate St. John)

A Few Things Seen

A red oak felled at Anderson Playground in Schenley Park, 30 Dec 2022 (photo by Kate St. John)

7 January 2023

This week’s rain dampened outdoor activities but there were still some things to see.

Chainsaw tree “trimming” continues in the city. This red oak had a hollow core so it was chopped down in late December at Anderson Playground in Schenley Park. Can you count the rings and determine its age?

On 3 January rain flecked the camera as Ecco stopped by for a visit. Notice how wet his head is!

On 4 January the rain finally stopped and the moon shone at 8pm.

When the cold snap ended on 28 December the ice thawed and the creeks began running again. Listen to the sound of Panther Hollow Run in Schenley Park on 30 December 2022.

(nest photos from the National Aviary snapshot camera at Univ of Pittsburgh, all other photos and video by Kate St. John)

Deer Density at a Glance

Tall columnar arborvitae along an alley in Kutztown, PA, 27 Nov 2022 (photo by Kate St. John)

12 December 2022

At Thanksgiving in Kutztown, PA I was stunned to see a solid wall of arborvitae bordering a neighborhood. In Pittsburgh’s East End, arborvitae is always bare from the ground to 4-5 five feet up, eaten by our overpopulated deer. Here’s a row of arborvitae at Schenley Park golf course.

Deer damage on arborvitae at Schenley Park golf course, 11 Dec 2022 (photo by Kate St. John)

Why didn’t deer browse the Kutztown trees? My guess is that they are the Green Giant variety of Western arborvitaes. Davey Tree explains:

Deer don’t care for Western arborvitaes, like green giant, steeplechase or spring grove. So, if you plant these, they may leave them alone.

Though, when deer are starving, they become less picky and will eat almost anything, including those deer-resistant arborvitaes. If deer are a big problem in your yard, avoid arborvitae altogether. Stop Deer from eating Arborvitae trees (even Emerald Green)

There are so many deer in Pittsburgh that indeed they eat almost anything. They even nibble on poisonous milkweed!

Kutztown has far fewer deer per acre.

The trees show deer density at a glance.

(photos by Kate St. John)

The Largest Living Organism is Dying of Deer

Pando in October snow, 2021 (photo by Beth Moon via Flickr Creative Commons license)

29 November 2022

In 1976 Jerry Kemperman and Burton Barnes discovered that 106 acres of quaking aspens (Populus tremuloides) in the Fishlake National Forest of Utah were actually all the same male plant, one root with thousands of suckers that grew into trees. It came to be known as Pando — “I spread.”

Quaking aspen, Pando, in fall (photo from Wikimedia Commons)

Pando weighs 6,600 tons making it the heaviest known organism on Earth and it is very old, though no one is sure whether it’s 10,000 or 80,000 or even a million years old.

Aerial image of the location of the single aspen tree, Pando (highlighted in green) at Fishlake National Forest, Utah (photo from Wikimedia Commons)

However, almost as soon as Pando was discovered researchers found that sections of it were not rejuvenating because new sprouts were being overbrowsed by deer. In that part of the U.S. the species is mule deer (Odocoileus hemionus).

Mule deer in Colorado (photo from Wikimedia Commons)

So they fenced it — twice — one fence in 2013, another in 2014.

Map of 2018 Pando study partially funded by U.S. Bureau of Land Management, Grant/Award Number: L21AC10369 (map downloaded from Wiley Online Library)

Then in 2018 Paul Rogers and Darren McAvoy of Utah State University conducted a followup study sampling Pando’s health inside and outside the deer exclosure fences and concluded that the fencing was not working.

According to September 2022 Sci.News “The unfenced areas are experiencing the most rapid aspen decline, while the fenced areas are taking their own unique courses — in effect, breaking up this unique, historically uniform, forest. … Fencing alone is encouraging single-aged regeneration in a forest that has sustained itself over the centuries by varying growth.”

“One clear lesson emerges here: we cannot independently manage wildlife and forests.”

Sci.News, October 2018: Pando, World’s Largest Single Organism, is Shrinking

Aldo Leopold’s experience in his early career when he worked to eradicate wolves from the American West changed his perspective on trees and deer. At one point he shot an old female wolf and was there to see the green fire go out of her eyes as she died. He wrote …

I thought that because fewer wolves meant more deer, that no wolves would mean hunters’ paradise. But after seeing the green fire die, I sensed that neither the wolf nor the mountain agreed with such a view.…

I now suspect that just as a deer herd lives in mortal fear of its wolves, so does a mountain live in mortal fear of its deer. And perhaps with better cause, for while a buck pulled down by wolves can be replaced in two or three years, a range pulled down by too many deer may fail of replacement in as many decades.

Aldo Leopold: Sand County Almanac, “Thinking Like a Mountain”

Pando’s days are numbered because new trees are not growing up to replace the old ones. This is how a forest dies.

(photos from Wikimedia Commons, map from Wiley Online; click on the captions to see the originals)

Most of the Trees Are Bare

Most of the trees are bare on this Schenley Park hillside, 6 Nov 2022 (photo by Kate St. John)

10 November 2022

In Pittsburgh the wind blew all day last Saturday with gusts as high at 35 mph. By Sunday morning, 6 November, most of the trees were bare.

I confirmed this at my favorite “leaf gauge” hillside in Schenley Park, above, after hiking at Hays Woods where bare trees sheltered the still-green leaves of invasive honeysuckle.

Most of the trees are bare inside Hays Woods, 6 Nov 2022 (photo by Kate St. John)

Deciduous conifers are finally showing their own fall colors. Larches are yellow, dawn redwoods (Metasequoia glyptostroboides) are orange.

Deciduous needles on a dawn redwood, 7 Nov 2022 (photo by Kate St. John)

The needles were dropping fast from this one in front of Phipps Conservatory.

Dawn redwood at Phipps, 7 Nov 2022 (photo by Kate St. John)

Meanwhile half of the ginkgos (Ginkgo biloba) along Schenley Drive still had leaves.

Ginkgos along Schenley Drive, 7 Nov 2022 (photo by Kate St. John)

Last year they weren’t bare until 20 November, below, but I predict they will be earlier this year.

Ginkgo trees lost their leaves later in 2021. This is 20 Nov (photo by Kate St. John)

Even if I couldn’t see them I can hear a clue that most of the trees are bare. The sound of leaf blowers fills my neighborhood. Maybe yours, too.

Sound of a leaf blower, Pittsburgh, 8 Nov 2022 (recorded by Kate St. John)

(photos and audio by Kate St. John)

Fall Color This Week

Sunrise in Pittsburgh, 28 October 2022 (photo by Kate St. John)

29 October 2022

Fall color was brilliant this week, especially at sunrise.

Bright red was gone from our hillsides as the maples faded but other leaves took up the slack in yellow and orange. Below:

  • Bottlebrush buckeyes are yellow in Schenley Park.
  • Japanese knotweed is yellow-orange at Duck Hollow.
  • Blue-green porcelain berries were eagerly eaten by migrating robins.
  • Red honeysuckle berries attracted cardinals and house finches.
  • Confused flowers! Forsythia bloomed along the Nine Mile Run Trail even though its leaves were a deep purple-red.
  • Red oaks are red-orange in Schenley Park.
Bottlebrush buckeye leaves turn yellow in Schenley Park, 25 October 2022 (photo by Kate St. John)
Fall color, Japanese knotweed, Duck Hollow, 27 October 2022 (photo by Kate St. John)
Porcelain berry fruit, Nine Mile Run Trail, 27 October 2022 (photo by Kate St. John)
Honeysuckle fruit, Nine Mile Run Trail, 27 October 2022 (photo by Kate St. John)
Forsythia blooming in late October, NMR Trail, 27 October 2022 (photo by Kate St. John)
Fall color, Schenley Park from Panther Hollow Bridge, 25 October 2022 (photo by Kate St. John)

A week from now the trees will be half bare.

(photos by Kate St. John)

Seen This Week

Fall leaves, Schenley Park, 12 Oct 2022 (photo by Kate St. John)

15 October 2022

Fall colors were looking good in the City of Pittsburgh this week. A maple in Schenley Park turned shades of orange and red while the sunrise worked to match it.

Sunrise on 12 Oct 2022 (photo by Kate St. John)

This acorn in Schenley Park is a squirrel’s dream come true, the largest acorn native to North America. Bur oaks (Quercus macrocarpa also spelled burr oak) were planted in several places in the park more than 100 years ago, most notably at the main trail entrance near Bartlett Playground. This species withstands harsh conditions and is one of the most drought resistant oaks.

Bur oak acorn, Schenley Park, 9 Oct 2022 (photo by Kate St. John)

Goldenrods are blooming in the small meadow near Bartlett Playground.

Goldenrod in meadow, Schenley Park, 12 Oct 2022 (photo by Kate St. John)

During my walk to Schenley Plaza on 11 October I saw a peregrine fly toward Heinz Chapel’s scaffolding and disappear among the dense rods.

Heinz Chapel scaffolding, 11 Oct 2022 (photo by Kate St. John)

If he hadn’t moved I would not have found him. Ta dah! (See inside red circle.)

Peregrine falcon perched (circled) on Heinz Chapel scaffolding, 11 Oct 2022 (photo by Kate St. John)

Amazingly he was easier to see through binoculars from Schenley Plaza tent. Too far for a photo.

(photos by Kate St. John)

Fluff Like Snow in June

Pile of cottonwood fluff in the hand (photo from Wikimedia Commons)

9 June 2022

It usually “snows” in late May in Pittsburgh but this year it happened in early June.

On 3 June a light breeze carried snow-like fluff above Nine Mile Run in Frick Park. I found a source in this open catkin that had fallen on the trail.

Eastern cottonwood pods burst open, Frick Park Nine Mile Run, 3 June 2022 (photo by Kate St. John)

Another had not fully opened before it fell.

Eastern cottonwood female catkin gone to seed, Frick Park Nine Mile Run, 3 June 2022 (photo by Kate St. John)

Both came from an eastern cottonwood tree (Populus deltoides) whose leaves look like this. There are only a few of cottonwoods in the Nine Mile Run valley but their seed dispersal is prodigious.

Eastern cottonwood leaves (photo from Wikimedia Commons)

Pittsburgh is barely inside the eastern edge of the cottonwood’s range so the trees and their fluff are not common here. Read more about them in this vintage article.

(photos by Kate St. John and from Wikimedia Commons)

Invasive Princess

Princess tree (Paulownia tomentosa) in bloom (photo from Wikimedia Commons)

This gorgeous tree with large violet flowers is blooming now in Allegheny County. It grows fast, provides shade, looks beautiful and smells sweet. What could go wrong?

One paulownia blossom with my hand for size comparison, Schenley Park, 23 May 2022 (photo by Kate St. John)

The princess tree (Paulownia tomentosa), also called empress tree or royal paulownia for Anna Pavlovna of Russia (1795-1865) is — or was — popular in ornamental gardens. It was first introduced to the U.S. from China in 1840 and planted in the eastern U.S. and Washington state.

Initially it was a gardener’s dream. It is easy to grow in full sun, thrives in many soil types including disturbed soil, is tolerant of drought and pollution and grows 15 feet per year. It also reproduces like crazy. One tree can produce 20 million winged seeds that are dispersed by wind and water.

Seed pods and seeds of Paulownia tomentosa (photo from Wikimedia Commons)

And …

Paulownia tomentosa’s ability to sprout prolifically from adventitious buds on stems and roots allows it to survive fire, cutting and even bulldozing in construction areas; making it difficult to remove from established areas.

Texas Invasive Species Institute: Paulownia tomentosa

This one was chopped down but it came back stronger than ever. Notice the huge leaves.

Paulownia tomentosa sprouts from a stump. Huge leaves! (photo from Wikimedia Commons)

Eventually botanists and gardeners realized that P. tomentosa is invasive. This map of paulownia’s occurrence in the U.S. …

Distribution of Paulownia tomentosa by county in U.S. (from EDDMapS)

… nearly matches the map of its State Invasive listings. Maryland and Massachusetts have outlawed it.

State Invasive Listings for Paulownia tomentosa (map from

Years ago I knew of only one princess tree in Pittsburgh, this one next to the Schenley Bridge near the corner of Frew Street and Schenley Drive.

Princess tree next to the Schenley Bridge at Frew Street and Schenley Drive, 23 May 2022 (photo by Kate St. John)

Then a few years ago a volunteer sprouted in Schenley Park near the tufa bridge over Phipps Run. When it reached 20 feet it was cut down and its roots were dug up. However, this spring there are four paulownias near the tufa bridge. The genie is out of the bottle. Uh oh!

Learn more about the invasive princess in this video from University of Maryland Extension, posted at

p.s. P. tomentosa has been suggested as a plant to use in carbon capture projects. Nooooo! Don’t do it!

(photos from Wikimedia Commons and by Kate St. John, maps from EDDMapS; click on the captions to see the originals)

What Tree Is This?

Hosechestnut in flower (photo from Wikimedia Commons)

19 May 2022

Trees with stacks of white flowers are drawing our attention this week in Pittsburgh. Perhaps you’re wondering “What tree is this? “

Horsechestnuts (Aesculus hippocastanum) originated in Greece but have been planted around the world for their beautiful flowers. When fertilized the flowers become the familiar shiny buckeyes I played with as a child.

Fruit of the horsechestnut (photo from Wikimedia Commons)

In Pittsburgh we call the tree a “buckeye” though it is just one of many buckeyes (Aesculus) in our area including natives of North America: yellow, Ohio, and bottlebrush.

A close look at horsechestnut flowers reveals that some have yellow centers, others red.

Closeup of horsechestnut flowers (photo from Wikimedia Commons)

Bees see and are attracted to yellow, not red, so when a horsechestnut flower is fertilized it turns red. The flowers are …

Are there red flowers on the tree? Come back in early fall to collect the buckeyes.

(photos from Wikimedia Commons; click on the captions to see the originals)