Category Archives: Trees

The Leaves Lingered

Though most trees are bare, the hilltop oaks still have leaves on 30 Nov 2021 (photo by Kate St. John)

4 December 2021

Last weekend many homeowners in Pennsylvania were annoyed that they had to rake leaves after Thanksgiving. A decade ago this would never have happened because the trees were bare by 5 November. Nowadays the leaves linger. Our warmer climate keeps them on the trees.

The delay in leaf drop has been increasing for at least a decade. In 2008-2012 most of the trees were bare by 2 or 4 November. In 2017-2021 the trees waited until 25-30 November. (*)

Meanwhile the height of fall color is later and lackluster. Twenty years ago we used to go leaf peeping on Columbus Day. This year the height of color in Schenley Park was on 13 November and not particularly breathtaking.

Fall color at Westinghouse Memorial in Schenley Park, 13 Nov 2021 (photo by Kate St. John)

Trees need a particular weather combination to trigger fall colors and leaf drop.

The timing and quality of color changes depend on a combination of temperatures, precipitation and sunlight. The best fall color displays occur after sunshine-filled days and cooler nights, following healthy doses of rain in the summer.

Washington Post: Fall foliage flopping: How climate change is dulling and delaying your leaf peeping

But it was way too warm in October. In fact it was the world’s fourth warmest on record.

U.S. Temperature Outlook for October 2021 issued 30 Sep 2021 by National Weather Service

The leaves lingered and finally by 30 November 2021 most of the trees were bare. Note that this date and all dates mentioned above are assessments of this same hillside in Schenley Park.

More than half of the trees are bare, Schenley Park, 25 Nov 2021 (photo by Kate St. John)

Read more about the disappointment of this fall’s foliage — and the economic impact — at the Washington Post: Fall foliage flopping: How climate change is dulling and delaying your leaf peeping.

(photos by Kate St. John, map from the National Weather Service)

Seen This Week

Ginkgo turning yellow at Schenley Park, 13 Nov 2021 (photo by Kate St. John)

20 November 2021

This week we had a last blast of fall color, a partial lunar eclipse and a surprising confirmation of pigeon fertility. Here are a few scenes from 12-19 November.

The ginkgo trees (Ginkgo biloba) turned yellow and will probably drop their leaves in a single day. Red oaks and hickories made a bright splash of color at Phipps’ outdoor garden on Monday.

Red oak at Phipps garden, 15 Nov 2021 (photo by Kate St. John)

Some beech leaves were already brown though the leaf veins were still yellow. Beech leaves cling to the smaller trees all winter, becoming paper thin and rattling in the wind.

Beech leaves turn brown though the veins are still yellow, Schenley Park, 15 November 2021 (photo by Kate St. John)

On Wednesday 17 November four of us drove north hoping for water birds but were disappointed by the lack of bird activity, particularly after the clouds moved in. Colorful leaves were scarce in Crawford County, especially at Conneaut Outlet swamp where high water killed the trees. This scene says “November in western Pennsylvania.”

Conneaut Outlet, Crawford County, 17 Nov 2021 (photo by Kate St. John)

On 18 November I saw a pigeon feeding two babies at its nest on Filmore Street near the Cathedral of Learning. Yes, nesting in November! Feral rock pigeons (Columba livia) breed year round if there’s enough food — and there is at this pile of birdseed on the corner.

Birdseed for pigeons at S. Dithridge & Filmore, 18 Nov 2021 (photo by Kate St. John)

As expected the partial lunar eclipse was obscured by clouds in Pittsburgh at 4am on 19 November. Only a tiny bright uneclipsed sliver is visible. The clouds are lit from below by the city lights.

Partial lunar eclipse obscured by clouds. Only the bright sliver shows in Pittsburgh, 19 Nov 2021 (photo by Kate St. John)

More leaves fell this week but most of the trees are not yet bare. Here’s a week’s worth of change at Schenley Park, 12 and 19 November.

Maples are bare, oaks are red, Schenley Park, 12 Nov 2021 (photo by Kate St. John)
Not yet. Most of the trees are Not bare. Schenley Park, 19 Nov 2021 (photo by Kate St. John)

The leaves are hanging on about two weeks longer than they used to. When will most of the trees be bare in Pittsburgh? Soon.

(photos by Kate St. John)

Bitter Nuts

Bitternut hickory nuts with peeling and whole husk (photo by Kate St. John)

18 November 2021

In case you don’t think tree names are descriptive consider the bitternut hickory (Carya cordiformis). Closely related to pecans (Carya illinoinensis) the nuts are so unpleasant that even squirrels avoid them. That explains why I found so many on the ground at Yellow Creek State Park on 6 November.

I didn’t know what they were so I brought several home to identify them. The thin husk that splits just halfway up the hard shell is diagnostic for bitternut hickory. I cracked one open.

Bitternut hickory nuts: whole, cracked and still in husk (photo by Kate St. John)

It resembles a pecan, as it should since it’s a “pecan hickory.”

Bitternut hickory nut cracked open (photo by Kate St. John)

Is the nut bitter? I usually don’t sample wild food but why not? I tasted a tiny bit.

Yow! Bitter! Astringent. I washed out my mouth several times before the taste went away. No wonder squirrels avoid these. Wikipedia says rabbits eat them, though.

Bitternut hickory nutmeat (photo by Kate St. John)

Obviously the nuts are not valuable to humans but the wood is hard and durable, used for furniture, paneling, tool handles, ladders and for smoking meat — as in hickory-smoked bacon.

The smoke may be nice but not the bitter nuts.

Further reading: Here’s how to identify the bitternut hickory in winter.

(photos by Kate St. John)

Fall Colors, Frost, and Bad Air

Colorful trees at Moraine State Park, 3 Nov 2021 (photo by Kate St. John)

8 November 2021

Last week began as a warm colorful autumn and ended with frosty mornings. This week begins with bad air.

Before last week’s frost I found splashes of fall color including this amaranth in an unusual place at Phipps Conservatory. Click here to see where this red plant was growing.

Amaranth in an unusual spot at Phipps Conservatory, 30 Oct 2021 (photo by Kate St. John)
Colorful leaves at Schenley Park, 30 Oct 2021 (photo by Kate St. John)

On 4 November the leaves glowed yellow as the sun gained altitude at Frick. When the sun melted the frost, leaves quickly loosened and dropped from the trees.

Sun through golden trees on a frosty morning at Frick Park, 4 Nov 2021 (photo by Kate St. John)

On Saturday morning at Yellow Creek State Park the frost was beautiful, ephemeral and cold. Hoarfrost decorated the weeds in the parking lot.

Hoarfrost on a grassy weed, Yellow Creek State Park, 6 Nov 2021, 9:39am (photo by Kate St. John)
Hoarfrost at Yellow Creek State Park, 6 Nov 2021, 9:39am (photo by Kate St. John)

Frost remained in a tree’s shadow but not for long.

Frost in the shadow, Yellow Creek State Park, 6 Nov 2021, 9:49am (photo by Kate St. John)

Last week I re-learned how to dress for winter. This week will be warm with highs in the 60s, lows in the 40s, temperature inversions and bad air in Pittsburgh.

Roger Day captured these views of the Mon Valley yesterday morning, 7 November, from Frick Park’s Riverview overlook. The Allegheny County Health Department has issued an air pollution warning and the state DEP has issued a Code Orange warning. Read more here.

Edgar Thompson Works in Braddock pouring smoke, seen through smog at Frick Park, morning of 7 Nov 2021 (photo by Roger Day)
Inversion: Edgar Thompson Works in the distance, Frick Park, morning of 7 Nov 2021 (photo by Roger Day)
Inversion: Kennywood seen through smog from Frick Park, morning of 7 Nov 2021 (photo by Roger Day)

Don’t breathe!

(photos by Kate St. John & Roger Day)

Halloween Colors in Nature

Milkweed bugs, Sept 2021 (photo by Kate St. John)

31 October 2021

Some things are naturally black and orange like Halloween, often because they are poisonous. This is especially true for milkweed bugs (above) and monarch butterflies (below). The colors say “Notice me and stay away.”

Monarch butterfly on swamp milkweed, July 2014 (photo by Steve Gosser)

Red admiral butterflies are orange-red and dark brown, almost black. Their host plant is nettle. Are they poisonous?

Red admiral, Germany (photo from Wikimedia Commons)

Jack-o-lantern mushrooms (Omphalotus olearius) are well named for their color. Did you know the gills of these mushrooms glow green in the dark? Unfortunately it’s never dark enough to see this in Schenley Park where I found the mushrooms in late September.

Jack-o-lantern mushrooms in Schenley Park, 25 Sep 2021 (photo by Kate St. John)

Pumpkins are native to Central America while goats are native to southwest Asia and eastern Europe. Here the domesticated versions meet up. The goats win.

Goats eating discarded jack-o-lantern (photo by Rebecca Siegel via Wkimedia Commons)

Happy Halloween!

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

The Quaking Giant

Detailed image of the aspen Pando tree (photo by Lance Oditt via Wikimedia Commons)

21 October 2021

As the trees lose their leaves this autumn, consider this. There’s a tree in Utah that has lost its leaves at least 14,000 times.

Nicknamed Pando, it’s a quaking aspen (Populus tremuloides) that’s 14,000(*) years old and the largest known aspen clone. All its trunks come from a single root covering 106 acres. At 6,600 tons its the heaviest known organism on Earth.

Aerial map of Pando, the quaking aspen tree (image from Wikimedia Commons)

How did Pando do this? Learn more in this vintage blog: A 14,000 Year-Old Tree.

(*) Pando’s age is in dispute among scientists. It may be anywhere from 10,000 to 80,000 years old.

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

Which Ones Are Drupes?

Cherries (photo from Wikimedia Commons)

17 October 2021

In botany a drupe is a simple fleshy fruit that contains a single hard pit with a seed inside it.

Some of the photos in this article show drupes, some do not. Which is which?

White peaches with a cross section (photo from Wikimedia Commons)
Black walnuts just fallen from the tree (photo from Wikimedia Commons)
Avocado with a cross section (photo from Wikimedia Commons)
Green (unripe) and black (ripe) olives (photos from Wikimedia Commons)

Which are drupes? Leave a comment with your answer.

See the comments for the answer.

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

Seen This Week

Sunrise on Thursday 14 October 2021 (photo by Kate St. John)

16 October 2021

It’s been three and a half weeks since the September equinox and every day is shorter than the last. Sunrise draws attention because it’s later every day. On Thursday the sky turned red before the sun appeared.

In the half light after sunset Morela prepared to roost.

Morela is ready to leave for her roost, 13 October 2021, 6:59pm (photo from the National Aviary snapshot cam at Univ of Pittsburgh)

The days are the same length as in late February during peregrine courtship. Morela and Ecco visited the nest as if they are thinking of spring.

Morela and Ecco bowing, 13 October 2021, 6:14pm (photo from the National Aviary snapshot cam at Univ of Pittsburgh)

Meanwhile most plants and trees have set fruit, including this streetside Callery pear.

Callery pear fruit, 14 October 2021 (photo by Kate St. John)

And in Downtown Pittsburgh I found a directional message on our tallest building.

“There is the sky, so that must be Up.”

There is the sky so that must be Up, Downtown Pittsburgh, 13 October 2021 (photo by Kate St. John)

(photos by Kate St. John)

Inside the Bladdernut

3 October 2021

By October the seed pods of American bladdernut (Staphylea trifolia) are papery brown three-sided puffs.

American bladdernut seed pods, Schenley Park, 1 Oct 2021 (photo by Kate St. John) (background was blurred by portrait mode on my cellphone)

If you peel one apart it becomes three heart-shaped pieces. Each piece may hold one popcorn-like seed. Some pieces may be blank.

Outside of a single bladdernut paper shell (photo by Kate St. John)

Six months ago the bladders began as small dangling flowers less than 1/4 inch long. Notice the three-part leaves that give this native shrub or small tree its trifolia species name.

Flowers much magnified with trifolia leaves, Schenley Park, 17 April 2021 (photo by Kate St. John)

By late July the bladders were green and very puffy. Each section had its own distinct point.

Bladdernut seed pods, 28 July 2020 (photo by Kate St. John)

And then the bladders dried out.

Dried bladdernut, Schenley Park, 3 Oct 2021 (photo by Kate St. John)

American bladdernuts put so much effort into seed pods that it’s surprising to find they can spread by suckers, especially in their favorite habitats of floodplain woods or stream banks in eastern North America.

Range map of American bladdernut (image from Wikimedia Commons)

Visit Schenley Park this month to see the bladdernuts. Pull a seed pod apart and look inside.

(photos by Kate St. John, map from Wikimedia Commons; click on the caption to see the original)

This Tree Can Change Its Sex

Striped maple leaves (photo from Wikimedia Commons)

10 August 2021

Years ago when I learned that Jack-in-the-pulpit can change its sex from male to female and back again, I accepted this as the odd behavior of an odd flower. So I was stunned to learn that the striped maple (Acer pensylvanicum), a common understory tree in the Laurel Highlands, can change sex, too.

The striped maple’s current sex is evident in its flowers. These are male.

Striped Maple male flowers (photo by Rob Routledge, Sault College,

How does it change and when does it decide to do it? Adam Haritan describes the mystery in his 8-minute video at Learn Your Land.

p.s. They are called striped maples because their bark is striped.

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