Category Archives: Trees

The (Pittsburgh) Ginkgo Map

Trees
Ginkgo leaves in Schenley Park, 31 Oct 2022 (photo by Kate St. John)

11 November 2025

Ginkgo trees (Ginkgo biloba) are living fossils from the Triassic, the only plant in their division to survive into the modern age. Because they are extremely hardy, cope well with air pollution and confined root systems, and are beautiful in autumn, they are often planted in cities around the world. Pittsburgh has many ginkgo trees, perhaps because of our Smoky City past.

Ginkgo trees at Jewish Association on Aging, Garetta Street as seen from JHF Drive, 11 Nov 2017 (photo by Kate St. John)

For seven years, Pittsburgh writer and professor Mark Kramer has been mapping ginkgo locations, mostly in southwestern Pennsylvania. Through word of mouth he now has pin drops in 3 countries and 26 states.

Ginkgo Tree Tracker map by Mark Kramer, embedded from Google Maps

At this time of year, when the ginkgos are at their peak of yellow, Mark asks for more photos and locations.

NOTE: If you’re viewing this on mobile: There is a Facebook bug since October 2024 that prevents displaying embedded Facebook posts on mobile devices. Until Meta fixes it click here to see Mark’s post.

Do you know of a ginkgo that isn’t on his map? I do. It’s the row of trees pictured above.

Here’s how to contact Mark:

Seen This Week: The Last Fall Colors

Phenology, Plants & Fungi, Schenley Park, Trees
Black tupelo fruits and fall color, Schenley Park, 6 November 2025 (photo by Kate St. John)

8 November 2025

Fall color faded quickly after yesterday’s gusty winds blew all the best leaves off the trees. The colors were brilliant in Schenley Park on Thursday 6 November as seen in these photos.

Fall color in Schenley Park, 6 Nov 2025 (photo by Kate St. John)
Fallen sweetgum leaf, Schenley Park, 6 Nov 2025 (photo by Kate St. John)
Fall color in Schenley Park, 6 Nov 2025 (photo by Kate St. John)

We found yellow black walnut leaves at Moraine State Park on Monday 3 November. The leaves and stems felt soft because they are fuzzy.

Fall color on black walnut leaves, Moraine State Park, 3 Nov 2025 (photo by Kate St. John)

Yesterday Schenley Park was at “Half Leaf” — about 50% of the leaves had fallen — and the remaining leaves were not as brilliant. The colors have faded fast.

Beech trees are the last to show fading fall color, Schenley Park, 7 Nov 2025 (photo by Kate St. John)

Soon the only brilliant colors will be in the sky.

Fall color in the sky at sunrise, 7 Nov 2025 (photo by Kate St. John)

Seen This Week: Fall Color in Fruit and Leaves

Phenology, Plants & Fungi, Schenley Park, Trees
Green hawthorn fruits (probably Winter King cultivar), Frick Park, 28 Oct 2025 (photo by Kate St. John)

1 November 2025

This week the brightest fall color disappeared from the landscape as rain and wind took down the reddest leaves. This showed off many colorful fruits to attract attention.

Above, a hawthorn tree at Frick Environmental Center is loaded with bright red fruit. I believe this is a cultivar of the green hawthorn (Crataegus viridis) chosen for its winter hardiness.

Below, on Flagstaff Hill I found one tree that still had red leaves on Wednesday. Thursday’s rain and wind probably stripped it bare.

One red tree left on Flagstaff Hill, Schenley Park, 29 Oct 2025 (photo by Kate St. John)

Fragrant sumac (Rhus aromatica) was so colorful that even the bud scales looked red.

Fragrant sumac leaves and buds near Phipps, 29 Oct 2025 (photo by Kate St. John)

Euonymus fortunei, planted for beauty in a Shadyside yard, shows off its bright orange fruits. Unfortunately this Asian vine “is highly invasive and damaging in the U.S., causing the death of trees and forest in urban areas.”

Fruits of Euonumous fortunei, Shadyside, 30 Oct 2025 (photo by Kate St. John)

Less colorful but still interesting, milkweed seed pods opened at Moraine State Park. This one hadn’t blown away yet.

Milkweed seed pod open and ready to go, Moraine State Park, 27 Oct 2025 (photo by Kate St. John)

More changes are coming this week including FALL BACK clocks tonight.

Seen This Week: Fall Color in Sky and Leaves

Plants & Fungi, Trees, Weather & Sky
Sunrise in Pittsburgh, 19 October 2025 (photo by Kate St. John)

25 October 2025

Vibrant reds and oranges graced the sky and the forest in Pittsburgh this week.

Our region is in the midst of an oak-hickory forest so red-colored leaves can be scarce. Oaks turn dark red after most other trees are bare and hickories turn yellow, so I look forward to the moment when our few sugar maples turn red. It happened this week in Schenley Park, as you can see below.

Fall color on maples in Schenley Park, 23 Oct 2025 (photo by Kate St. John)
Fall color on maples in Schenley Park, 23 Oct 2025 (photo by Kate St. John)
Fall color along the Lower Trail at Schenley Park. Notice that it’s yellow. 20 Oct 2025 (photo by Kate St. John)
Fall color on maples in Schenley Park, 23 Oct 2025 (photo by Kate St. John)
Sunlight breaks through the background; fall color in Schenley Park, 23 Oct 2025 (photo by Kate St. John)

Two deer browsed near Schenley’s Upper Trail. One is already in her gray winter coat but so close to the trail that her camouflage didn’t matter. I would have missed the other deer (yellow arrow) except that it moved.

Two deer browsing in Schenley Park near the Upper Trail, 20 Oct 2025 (photo by Kate St. John)

Cold temperatures have ended this year’s spotted lanternflies so I was surprised to see one on the Panther Hollow Bridge. The air was so cold that didn’t move as I approached. Hah! I see you.

Spotted lanternfly, Schenley Park, 20 Oct 2025 (photo by Kate St. John)

p.s. Mary Kate reminded me that sweetgum trees are very pretty in the fall. I’ll try to get some pictures this coming week.

City Deer at the Highrise

Deer, Trees

18 October 2025

As I mentioned last month, deer in the City of Pittsburgh moved out of city parks and into the neighborhoods when archery season began on 20 September. Now that the hunt has been going for four weeks I’ve noticed two things.

This week I learned from a bow hunter that the few deer I see resting in Schenley Park are too young to hunt. Restrictions on antler size and “plumage” (coat indications) prohibit taking the ones I’ve seen. Apparently these individuals somehow know they are safe.

After four weeks of browsing neighborhood yards the pickings must be slim over in Shadyside. On Saturday 11 October a doe visited the Oakland highrise district to browse on the landscaping, slideshow above.

Since I don’t often look outside my window before dawn I’ve only seen this once before in March 2024. I’ll be watching for the next visit.

Seen This Week: Acorns and More

Songbirds, Trees, Weather & Sky
Burr oak acorns, Flagstaff Hill, Schenley Park, 17 September 2025 (photo by Kate St. John)

20 September 2025

There are so many oaks in Schenley Park that a few burr oaks (Quercus macrocarpa) are not noticeable until they drop their large, fringed acorns. Where did they come from? I looked up to find the tree, taller and broader than its neighbors.

Burr oak acorn, Flagstaff Hill, Schenley Park, 17 September 2025 (photo by Kate St. John)

The burr oak’s location does not have a good view so I sat beneath a large oak at the top of Flagstaff Hill overlooking Oakland. Based on acorns, leaves, and the history of landscaping in Schenley Park, my guess is that I sat beneath an English oak (Quercus robur).

(presumably) English oak acorns, Flagstaff Hill, Schenley Park, 17 September 2025 (photo by Kate St. John)

It’s a high mast year for this particular tree. The only way I avoided being hit by acorns was to sit with my back against the trunk!

Other sightings this week include birds Tuesday morning at Bird Lab’s Hays Woods banding which I wrote about on Wednesday’s blog: Hays Woods Birds Live up to Expectations.

Common yellowthroat at Hays Woods Bird Lab, 16 September 2025 (photo by Kate St. John)
Dotted line across the morning sky, Pittsburgh 17 Sept 2025 (photo by Kate St. John)

I rarely walk through the Heinz Chapel Memorial Garden but its fountain is attractive during the drought. On the way to the fountain I found an engraved paver stone with a non-traditional dedication.

Memorialized paver stone at Heinz Chapel, Univ of Pittsburgh, 17 Sept 2025 (photo by Kate St. John)

If you want to find this stone, enter the Heinz Memorial Chapel Garden from the Bellefield Avenue side (near the steps to Bellefield Ave) and look at the pavers along the left. (This photo does not include a view of the Will You Marry Me paver.)

Heinz Chapel fountain and garden benches (photo from Wikimedia Commons)

Trees That Love Heat

Climate Change, Trees
Crape myrtle trees in bloom, Texas (photo from Wikimedia Commons)

3 July 2025

While last week’s heat wave broke here on Friday, I was in Virginia where the heat persisted and was even more intense. The temperature got up to 99° in Virginia Beach with a heat index somewhere near 110°F. I don’t remember the number. I stayed indoors. Meanwhile all the plants and animals were stuck outside in adverse conditions but one ornamental tree was thriving. Crape myrtle loves heat.

Crape myrtle in Virginia (photo from Wikimedia Commons)

Crape myrtle (Lagerstroemia sp., also spelled crepe myrtle) is a small ornamental tree or shrub from Asia and the Indian subcontinent that is widely planted in southeastern Virginia. There are many species and many varieties bred for color and local conditions.

Crape myrtle in Loudon County, Virginia (photo from Wikimedia Commons)

The trees that thrive in Virginia Beach are not the same variety that survives in Pittsburgh. Pittsburgh is too cold for typical crape myrtle so we have to plant cold tolerant varieties. I hear they were slow to bloom during our cold spring.

Thirteen years ago I marveled at crape myrtle’s resilience as I melted in the Virginia heat. Learn more in this vintage article.

Crape myrtle, Smithfield, VA, 7 July 2012 (photo by Kate St. John)
Loves Heat

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Vegetative Embrace

Plants & Fungi, Trees
Woody vine embraces a tree branch, Raccoon Wildflower Reserve, 26 May 2025 (photo by Kate St. John)

2 June 2025

Animals embrace and release but when plants wrap around each other the result is often permanent. Sometimes an embrace is intentional, sometimes not.

Intentional
  • Almost like a snake, the woody vine pictured at top intentionally wrapped itself around a tree branch. But then it stopped growing and left the two locked in a vegetative embrace.
  • Dodder (Cuscata), pictured below, is a parasitic native annual in the morning glory (Convolvulaceae) family that intentionally wraps itself closely around a plant stem. It then inserts very tiny feelers between the cells and sucks nutrients from its host.  As an annual, it starts growing from seed but loses its soil-based roots when it has found a really good host.
Dodder more-than-embracing another plant, June 2017 (photo by Kate St. John)
  • Porcelain berry (Ampelopsis glandulosa) and grapevine intentionally drape themselves on trees and shrubs to lift themselves above the canopy. When this vine fell it embraced the oak.
Fallen vine embraces the oak it fell from, Moraine State Park, October 2022 (photo by Kate St. John)
  • Some plants have leaves that clasp the stem, circled in pink below. Botanists: Can you tell me the name of this plant? I forgot to note it when I took the photo at Raccoon Wildflower Reserve.
Alternate leaves clasp the stem, Raccoon Wildflower Reserve, 26 May 2025 (photo by Kate St. John)
Unplanned, Inadvertent

There are also inadvertent vegetative embraces, some of which are temporary.

  • Two trunks of the same species grew so close together that they fused at the base in this permanent embrace.
Two trees growing in a close embrace, January 2010 (photo by Kate St. John)
  • When this skunk cabbage put up shoots in the spring, one of them speared a dead leaf whose ribs now prevent the skunk cabbage from opening. Temporary embrace? I like to rescue these plants, especially mayapple and trillium, by pulling off the dead leaf. I can’t remember if I rescued this one.
Dead leaf, speared by an emerging skunk cabbage leaf, prevents it from unfurling, April 2025 (photo by Kate St. John)

Woolly Gall on an Oak

Insects, Spiders, Trees
Woolly oak gall, Raccoon Wildflower Reserve, 25 May 2025 (photo by Kate St. John)

31 May 2025

Oak apple galls are shiny and brown so I was surprised to find this fuzzy one on a white oak stem. This not a fuzzy version of the oak apple gall. This is a woolly oak gall made by a completely different species of gall wasp (family Cynipidae).

Woolly oak galls are made by Callirhytis seminator, “the wool sower,” which places its galls only on white oaks and only in the spring.

The wasps are tiny, 1/8″ long, and have many predators including larger parasitic wasps. They do not sting humans.

Wool sower gall maker (Callirhytis seminator), Lisa Ames University of Georgia via bugwood.org

Gall wasps have a two-generation alternating cycle: One generation produces stem galls, and the wasps that emerge from that stem gall mature and lay their own eggs in leaf galls. The wasps that emerge from the leaf gall mature and produce stem galls. Scientists do not know what the alternate wool sower wasp gall looks like.

— WIkipedia: Callirhytis seminator account

The gall I found and the one pictured below were made by the stem-gall generation.

Woolly oak gall, Jim Baker, North Carolina State University via bugwood.org

If you open the gall it has seed-like structures inside that are actually plant material, not the insect. The larvae are white and fat, have no legs.

Interior of a woolly oak gall, made by Callirhytis seminator, Jim Baker, North Carolina State University via bugwood.org

As the gall matures it turns pink.

Woolly oak gall made by Callirhytis seminator (photo by Terry S. Price, Georgia Forestry Commission via bugwood.org)

If I go back to Raccoon Wildflower Reserve in a few weeks and find the same tree the gall won’t look the same. Will it even be there?

Why Did This Tree Fall?

Schenley Park, Trees
Fallen red oak from 29 April storm, Falloon Trail Schenley Park, 20 May 2025 (photo by Kate St. John)

27 May 2025

On my walks through Schenley Park I am often curious about the demise of sturdy trees. Why did this intact red oak fall?

The simple answer is that it blew over during the 29 April wind storm as did so many other trees in Pittsburgh. But a closer look reveals a weakness that contributed to its demise.

Looking at the root ball, there are no obviously broken big roots that would have anchored the tree to the ground and it appears that the trunk is hollow. Something “ate” the tap and anchor roots. When a big wind came the tree fell over. My guess at the culprit is the fungus armillaria or honey mushrooms.

Weakness that made it fall: No long roots on root ball, 20 May 2025 (photo by Kate St. John)

Along the same trail I found this structurally compromised tree still standing. Only the bark, cambium and sapwood are holding it up.

Disintegrating red oak, Schenley Park, 20 May 2025 (photo by Kate St. John)

Inside, the trunk is hollowed out by major insect damage. Now that the exterior is cracked it won’t take much wind to knock the tree over.

Weakness causing disintegration: Hollowed from major insect damage, 20 May 2025 (photo by Kate St. John)

I’m always amazed when a tree snaps in the middle of the trunk. This black cherry fell over in May 2014 to reveal white sheets — armillaria — that weakened the tree.

Black cherry snapped in the middle, 30 May 2014 (photo by Kate St. John)

Read more about it in this Quiz+Answer from June 2014.

What Made This Tree Fall Over?

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