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.
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.
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.”
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.
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.
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.
The leaves are hanging on about two weeks longer than they used to. When will most of the trees be bare in Pittsburgh? Soon.
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.
It resembles a pecan, as it should since it’s a “pecan hickory.”
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.
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.
On Saturday morning at Yellow Creek State Park the frost was beautiful, ephemeral and cold. Hoarfrost decorated the weeds in the parking lot.
Frost remained in a tree’s shadow but not for long.
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.
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.”
Red admiral butterflies are orange-red and dark brown, almost black. Their host plant is nettle. Are they poisonous?
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.
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.
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.
Meanwhile most plants and trees have set fruit, including this streetside Callery pear.
And in Downtown Pittsburgh I found a directional message on our tallest building.
By October the seed pods of American bladdernut (Staphylea trifolia) are papery brown three-sided puffs.
If you peel one apart it becomes three heart-shaped pieces. Each piece may hold one popcorn-like seed. Some pieces may be blank.
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.
By late July the bladders were green and very puffy. Each section had its own distinct point.
And then the bladders dried out.
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.
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)
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.
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)