Category Archives: Trees

Opal Inside

Trees, Winter Weeds & Trees
Common hackberry fruit (by Kate St. John) and precious opal (from Wikimedia Commons)

27 November 2024

November is a good time of year to look for hackberry trees in Pittsburgh and examine their fallen fruit. By now the pulp has worn off the pits, but unlike wooden cherry pits hackberries’ are like white seashells with a microscopic lattice of opal inside.

Common hackberry pits: one whole, one opened (photo by Kate St. John)

Learn about these amazing structures in this vintage article.

Tiny Opals

Then go find a hackberry tree (and an electron microscope).

Hackberry bark and bare branches make it easy to identify the tree, even in winter. The bark has ridges and the ridges have growth lines.

Hackberry bark has ridges. The ridges have growth lines (photo by Kate St. John)

Up in the bare branches, hackberry trees sometimes have twig formations called witches brooms “produced by the effects of an eriophyid mite (Aceria celtis) and/or an associated powdery mildew producing fungus (Sphaerotheca phytoptophila)” — from bugwood.

Witches brooms on hackberry by Whitney Cranshaw, Colorado State University from Bugwood.org

Finding an electron microscope to view the opal is a much harder task.

Seen This Week: Fruits and Seeds

Musings & News, Phenology, Plants & Fungi, Trees
“Monkey balls” = fruit of osage orange tree, Schenley Park, 20 Nov 2024 (photo by Kate St. John)

23 November 2024

Now that the leaves have fallen fruits and seeds are prominent in the landscape.

Osage orange (Maclura pomifera) trees have prolific fruit this fall but nothing eats the “monkey balls” so they just lay on the ground to rot. If you crack one open it has sticky latex inside. Who would eat this fruit? The answer is in the video at the end!

The fruiting body of a shaggy mane mushroom (Coprinus comatus) poked up among the leaf litter near Five Points at Moraine State Park.

Fruiting body of Shaggy Mane mushroom, Moraine State Park near Five Points, 18 Nov 2024 (photo by Kate St. John)

Red fruits of oriental bittersweet (Celastrus orbiculatus) are a favorite food of migrating American robin, protected by a hard yellow-orange skin that pops off in sections. It looks like a squirrel gnawed off this branch and lost his meal.

Fruit of oriental bittersweet, 18 Nov 2024 (photo by Kate St. John)

Late boneset has gone to seed in Schenley Park.

Late boneset seeds surrounded by fluff, Schenley Park, 20 Nov 2024 (photo by Kate St. John)

Just a few trees still have leaves. I found this colorful sweetgum along a sidewalk at CMU. Someone ripped a piece off the yellow leaf.

Colorful leaves on sweetgum, 20 Nov 2024 (photo by Kate St. John)

BONUS! Who eats monkey balls?

video embedded from Ghosts of Evolution on YouTube

Some Plants Are Simply Female

Plants & Fungi, Trees
Female spicebush with berries, 25 Sept 2017 (photo by Kate St. John)

21 November 2024

In the garden we often grow “perfect” flowers such as roses, lilies and tulips with male and female parts in every flower. However, many woody shrubs and trees have single sex flowers. Some species grow both sexes on the same tree, others have only one sex on an entire plant. And so, some plants are simply female.

Compare this “perfect” bisexual flower diagram …

Diagram of a flower with both female and male parts (image from Wikimedia Commons)

… to single sex flowers.

Diagrams of female and male flowers (altered from the perfect flower on Wikimedia Commons)

Monoecious species have both flower sexes on the same plant. Examples include hickory and pecan trees, cucumbers and pumpkins, cherries, common grape vine and corn (maize).

Dioecious plants produce only male or female flowers on individual plants and only the female plants produce fruit. Examples include gingkos (stinky fruit from female trees!) …

Fruit and fallen leaves from a female gingko tree (photo from Wikimedia Commons)

… and holly trees –> You can’t get holly berries if you have only one tree.

Holly leaves and berries (photo from Wikimedia Commons)

Knowing this, you can sex dioecious plants in the fall. And here we are with spicebush.

Sexing Spicebush

Seen This Week: Sun, Clouds, Acorns

Doves & Chickens, Phenology, Plants & Fungi, Schenley Park, Trees
Red oak acorns rained on us at Biddle’s, 4 Nov 2024 (photo by Kate St. John)

9 November 2024

It’s an abundant year for red oak acorns, also called a “big mast year.” The acorns pictured above rained on us while we sat outdoors at a coffee shop. Their parent tree shades the tables in summer but is not much fun this autumn.

In two days at Schenley Park: Sun through yellow trees on Tuesday. Overcast skies and russet oaks on Wednesday.

Sun through the trees at Schenley Park on Tuesday 5 Nov 2024 (photo by Kate St. John)
Overcast sky, russet oaks and leafless trees at Schenley Park on Wednesday 6 Nov 2024 (photo by Kate St. John)

I took a picture of a bird! An unusual, piebald pigeon.

Piebald pigeon from the side, 5 Nov 2024 (photo by Kate St. John)

The pattern extends to the back of its head.

Piebald pigeon from the back, 5 Nov 2024 (photo by Kate St. John)

In an August article, Grass Carpet in the Woods, I mentioned that “After Japanese stiltgrass goes to seed in early fall it dies and becomes a brown drape over the landscape in winter.” Well, here it is draping part of Frick Park near Wilford’s Pines.

Dead Japanese stiltgrass draping the landscape at Frick Park, 7 Nove 2024 (photo by Kate St. John)

Gingko Leaves Drop All At Once

Phenology, Trees
Ginkgo leaves beneath the trees, 6 Nov 2024 (photo by Kate St. John)

8 November 2024

In Pittsburgh this week the ginkgo trees (Ginkgo biloba) began to drop their leaves. I found a cheerful yellow carpet under gray skies on Wednesday.

Ginkgo leaves coat the ground; still more to come, Schenley Park, 6 Nov 2024 (photo by Kate St. John)

Other trees lose their leaves gradually or in the wind, but ginkgos can drop them all at once on a single day of calm weather. I tried to capture the “snowing” leaves in this 2017 video. Not very many.

video by Kate St. John in Nov 2017

@MyDailyNature does a better job of showing them fall including slow motion.

video embedded from MyDailyNature on YouTube

Get out soon to watch the ginkgos before the leaves are gone.

p.s. Did you know that gingkos are living fossils? Here’s more:

Native to East Asia, Ginkgo biloba is the last living species in the order Ginkgoales, which first appeared over 290 million years ago. Fossils very similar to the living species, belonging to the genus Ginkgo, extend back to the Middle Jurassic epoch approximately 170 million years ago. The tree was cultivated early in human history and remains commonly planted, and is widely regarded as a living fossil.

— Wikipedia: Ginkgo bilboa account

Alien Plants Stand Out in November

Phenology, Plants & Fungi, Trees
Native maple (orange) and alien plants (green) along the trail at Hays Woods, 2 Nov 2024 (photo by Kate St. John)

7 November 2024

This brilliant orange maple stood out at Hays Woods last weekend but when I examined the photo I realized there’s a lesson in this picture.

The native trees are either bare or, like the maple, on their last hurrah. Meanwhile, there are leafy green plants in the understory whose seasonal cycles do not match Pittsburgh’s. The green ones are aliens.

Notice the difference in the slideshow below. Natives are outlined in white, aliens in pink. The easy-to-see aliens are bush honeysuckle and porcelainberry.

Alien plants often leaf out early and drop leaves late. As our climate warms up they have an advantage over cautious native plants whose seasonal cycles expect frost.

In the days ahead most native plants will lose their leaves(*) and the only green left will be the aliens.

Honeysuckle still green beneath bare trees at Hays Woods, 6 Nov 2022 (photo by Kate St. John)

In November, alien plants really stand out.

(*) p.s. Though oaks and beeches lose most of their leaves, they retain some leaves through the winter.

Seen This Week: Autumn Colors

Phenology, Schenley Park, Trees, Weather & Sky
Fall color of pawpaw leaves, Schenley, 25 Oct 2024 (photo by Kate St. John)

26 October 2024

Fall color is so spectacular in Pittsburgh this week that many of us have been snapping pictures everywhere we go. Here are just a few of the colorful leaves and trees I’ve seen in town.

Pawpaw leaves are turning bright yellow in Schenley Park while Virginia creeper is red along the Three Rivers Heritage bike trail at Herrs Island.

Virginia creeper at Herrs Island back channel, 22 Oct 2024 (photo by Kate St. John)

Sunlight reflecting on the water made rippling lights in the trees on 22 October. It was so warm you can hear crickets.

Ripples in the trees, 22 Oct 2024 (video by Kate St. John)

Yesterday in Schenley Park the trees were yellow or red depending on species.

Scene on the Upper Trail, 25 Oct 2024 (photo by Kate St. John)
Scene on the Serpentine, 25 Oct 2024 (photo by Kate St. John)

Not to be outdone by autumn leaves, the sky turned orange at sunrise on Saturday.

Sunrise, 25 Oct 2024 (photo by Kate St. John)

Sunrise is after 7am now. We’ll “fix” that next weekend when we turn the clocks back.

Seen This Week: Late Flowers, Acorns, Crows

Crows & Ravens, Phenology, Plants & Fungi, Schenley Park, Trees
Insect on New York aster, Toms Run, 16 Oct 2024 (photo by Kate St. John)

19 October 2024

This week brought:

  • Fall colors and the first piles of fallen leaves
  • Late flowers and insects
  • “See Your Breath” cold mornings
  • The first juncos … and …
  • Several thousand crows in Oakland.

In photos, late asters attracted an insect at Toms Run and morning sun slanted through the trees in Schenley Park.

Fall colors and fallen leaves, Schenley Park, 18 Oct 2024 (photo by Kate St. John)

Many trees are changing color. The oaks aren’t there yet but they have dropped their acorns leaving empty acorn cups on the branches. It’s a big mast year for red oaks in Pittsburgh.

Red oak leaves and acorn cups, 13 October 2024 (photo by Kate St. John)

A rhododendron in Shadyside is confused. Is it spring?

Confused rhododendron blooming in Pittsburgh, 13 Oct 2024 (photo by Kate St. John)

This week crows were absent from Oakland during the day but arrived in huge flocks at dusk, staging on rooftops before flying to the roost. I fumbled to photograph them on the RAND Building last Sunday. This is only a fraction of the flock that flew away.

Crows make a stop on the RAND building before sunset, 13 Oct 2024 (photo by Kate St. John)

Obviously they’ve been roosting on Pitt’s campus. I found evidence below trees at the Pitt Panther statue. The Crows Slept Here Last Night.

Evidence at Pitt that The Crows Slept Here Last Night, 17 October 2024 (photo by Kate St. John)

What is a Wolf Tree?

Trees
White pine “Wolf Tree” in Red Rocks Park, South Burlington, Vermont, 2006 (photo from Wikimedia)

10 October 2017

When Europeans arrived in Pennsylvania the first thing they did was clear the forest for farms. 150 years ago the focus changed from chopping for farmland to clear-cutting to sell the wood. Clear-cutting ended in the complete deforestation of Pennsylvania in 1900-1920. Other than small patches of old growth forest, such as the one at Cook Forest, the Pennsylvania woods you see today is just 100+ years old.

A few old trees remained in unlikely places. Farmers sometimes left one tree in a field as shade for the animals or left a tree standing at the boundary line.

A future wolf tree: Lone tree in a field provides shade for the cattle (photo from Wikimedia Commons)

When the farm was abandoned the forest grew back and surrounded the lone tree. At top an ancient white pine is surrounded by a younger Vermont forest. Lone trees in Pennsylvania tend to be oaks.

In the late 20th century foresters dubbed them “wolf trees” because they believed that these huge older trees were “exhausting forest resources and should be eradicated to make way for profitable wood.” Eventually perceptions changed and wolf trees are now appreciated.

In 2015 I took a picture of a wolf tree at Cedar Creek Park in Westmoreland County. Nine years ago it had already been dead a long time and pieces of it were falling.

An old dead "Wolf Tree" at Cedar Creek Park (photo by Kate St.John)
An old “Wolf Tree” at Cedar Creek Park, Sept 2015 (photo by Kate St.John)

In subsequent visits to Cedar Creek I didn’t pay attention to this tree. I wonder how much of it still stands. I’ll have to go and see. (p.s. UPDATE on 15 Oct 2024: Mark Bowers checked and the tree is still there!

Read more about the changing attitudes about wolf trees at Berkshire Natural Resources Council: Debunking Wolf Trees

Appalachia’s Mango Ripens Next Month

Insects, Phenology, Trees
Pawpaw fruits on the tree (photo from Wikimedia Commons)

27 August 2024

I came up with today’s slightly inaccurate title when I heard WESA’s piece on Pennsylvania’s secret tropical fruit, the pawpaw or “hillbilly mango.” In fact, pawpaws are not mangoes — they just taste like it — and their range is much wider than Appalachia. However it is true that they ripen in September.

Pawpaw range map from Wikimedia Commons

Pawpaws (Asimina triloba) are the quintessential wild fruit for browsing animals that eat the only ripe fruit on the branch and then move on. The fruit tastes like mango and has the consistency of banana. But don’t eat the seeds. They are poisonous.

Pawpaw cut open to show the fruit and seeds (photo from Wikimedia Commons)

Pawpaws defy commercial agriculture.

  • The skin is thin and bruises easily so they cannot be shipped.
  • Pawpaws don’t ripen all at once. You must come back later for the next batch because …
  • If you pull a hard, unripe fruit from the tree it will never ripen.
  • Pawpaw fruits lose their flavor if you heat them.
  • The bark, leaves, fruit and seeds of pawpaw trees contain the disabling and potentially lethal neurotoxin annonacin so …
  • Do not dry or cook down the fruit because that concentrates the compound that — fortunately — makes you vomit. (see more in the WESA article).

However, the neurotoxin is a benefit for zebra swallowtails (Eurytides marcellus) whose only host plant is the pawpaw tree. Zebra swallowtail caterpillars eat pawpaw leaves, become toxic themselves and are protected from predators.

Zebra swallowtail in spring (photo from Wikimedia Commons)
Pawpaw Festivals in September

If you want to eat a pawpaw and learn more about them, your best bet is at an upcoming Pawpaw Festival. The complete schedule of 12 festivals plus additional events are at Heppy.org: 2024 Pawpaw Festivals and Events. Here are a few close to Pittsburgh on the Heppy.org list in order of occurrence.

  • Ohio Pawpaw Festival in Albany, Ohio, 13-15 Sept
  • Paw Paw Festival in Duncansville, PA, 22 Sept, 9a-4p
  • West Virginia Pawpaw Festival, Core Arboretum, Morgantown, WV, 28 September
Pittsburgh has two notable pawpaw enthusiasts:

Andrew Moore wrote the book on pawpaws in 2015. Pawpaw: In Search of America’s Forgotten Fruit. If you want to know about pawpaws this is the book to read!

Book cover. Pawpaw: In Search of America’s Forgotten Fruit by Andrew Moore

Gabrielle Marsden is restoring zebra swallowtail butterflies to southwestern PA by planting pawpaw trees and encouraging others to do the same. Her YouTube channel is here. She also has two upcoming events:

Pawpaw Pathways poster (image from Wikimedia Commons)

Still curious about pawpaws? Learn more at this vintage blog.

Eat Pawpaws in September

p.s. Thanks to John English for pointing out the WESA article.