Saturday blogs usually show what I’ve “Seen This Week” but I have only one worthy photo, shown above. For the rest I’ve chosen sights that are timely for the season and seen at some point.
This Wednesday the water was low in the Monongahela River at Duck Hollow, just as it is in this photo from Nov 2020. However the sky was not so blue and it was very cold!
Wednesday’s low was 21°F but today will warm to nearly 60°F. No frost today like the bit shown below from Nov 2021.
The trees are bare now and showing off their silhouettes. Here are three typical sights on the cusp of December.
You can identify young American elm trees by their twig arrangement that look like fish skeletons.
Black locust trees are always gnarly but this one was made worse when it was trimmed away from the utility wires in 2012.
Last month shagbark hickories (Carya ovata) put on a show in Pittsburgh’s parks with bright yellow leaves and fallen nuts.
The thick green husks began to turn brown immediately and peel off in quarter-moon sections. This piece of husk sat indoors for more than a month before I took a photo of its interior. The dark brown exterior is visible at the bottom edge.
If a nut lasts through the winter its husk looks quite worn out by March. This one was probably uneaten for a good reason.
Shagbark nutshells are slightly oval with a remnant stem and four ribs. When I cracked open the nut I collected, it was a dud. Maybe an insect got to it. This Wikimedia photo of a sawed nut shows the meat.
Though shagbark hickory nuts taste good and can substitute for pecans, shagbarks are not cultivated because …
They are unsuitable to commercial or orchard production due to the long time it takes for a tree to produce sizable crops and unpredictable output from year to year. Shagbark hickories can grow to enormous sizes but are unreliable bearers.
C. ovata begins producing seeds at about 10 years of age, but large quantities are not produced until 40 years and will continue for at least 100. Nut production is erratic, with good crops every 3 to 5 years, in between which few or none appear and the entire crop may be lost to animal predation.
Interestingly, shagbarks (Carya ovata) and pecans (Carya illinoensis) can hybridize in the wild though the hybrids usually don’t produce nuts.
Shagbark hickories are easy to identify by their shaggy bark. Just look up and you’ll see it peeling from the trunk. Young trees can fool you, though, because they have smooth bark (click here to see young bark).
Shagbarks are one of the first native trees to leaf out so their sap runs early in the spring. Yellow-bellied sapsuckers (Sphyrapicus varius) take advantage of this and drill the trees as they migrate north. The birds move sideways around the trunk as they drill in a ring around the tree. The trees heal the wounds by producing callus tissue that grows outward, almost like lips. These attract the the sapsuckers who then drill the same rings year after year.
If you’ve spent a lot of time in the woods chance are you’ve see trees kissing. The fusion of their trunks in what looks like a kiss is called inosculation from the Latin word for kiss.
University of New Hampshire explains how it occurs:
Inosculation happens when the friction between two trees causes the outer bark of each tree to scrape off at the point of contact. The trees respond by producing callus tissue that grows outward, thereby increasing the pressure between the two trees. This pressure, along with the adhesive nature of sap or pitch that exudes from the wounds, reduces the amount of movement at the point of contact. The cambia layers from the two trees come in contact and the vascular tissues become connected, allowing for the exchange of nutrients and water.
Though I’ve seen fused trees several times, I have only one photo of a pair “kissing,” fused twice at Raccoon Creek State Park in February 2015. The date is notable because that hike is also the last time I saw a long-eared owl.
An extreme case tweeted by Science girl @gunsnrosesgirl3 reminded me of the phenomenon. The smaller tree on the left does not touch the ground and is completely sustained by the larger one that’s holding it up. The embedded tweet below does not show that the smaller tree is cut off so click here to see a larger photo.
On Wednesday I found a yellow carpet on Elmer Street. Ginkgo trees were shedding their leaves all at once.
The ground was gorgeous and so were the branches.
Some trees were already bare. Some were yet to come.
But there were hazards beneath this beauty. Ginkgos are dioecious (with separate sexes) and the females produce fruits that smell like vomit. Landscapers try to plant only male trees but there was a female in this mix.
I didn’t pay attention until I stepped on a fruit and felt it pop beneath my heel. Yuck! The stinky flesh stuck in the treads of my shoe so I searched for a puddle to stomp in, too preoccupied to take a picture of the fruits. These are from Wikimedia.
Ginkgos were planted along Pittsburgh’s street during the Smoky City era because they’re one of the few trees that do well in polluted air. We can expect them continue for 100s of years.
In 2020, a study in China of ginkgo trees up to 667 years old showed little effects of aging, finding that the trees continued to grow with age and displayed no genetic evidence of senescence, and continued to make phytochemicals(*) indefinitely.
(*) Phytochemicals are chemical compounds produced by plants, generally to help them resist fungi, bacteria and plant virus infections, and also consumption by insects and other animals. Gingkos have great immune systems even when more than 600 years old.
Black walnut trees (Julgans nigra) are common in the Pittsburgh area. Their nuts are always ready to eat in time for the holidays.
In September the fruit was still on the trees while we searched for fall warblers among the leaves.
By the end of October the fruit had fallen and started to look bruised. Eventually the husks turned black.
But most black walnuts aren’t abandoned that long. Squirrels gather them for winter food and eat a few along the way.
Squirrels know that they have to open the shell on both sides to get all of the nut meat.
The meat does not come out easily! It usually breaks into small pieces on the way out and is never the perfect shape of grocery store walnuts.
The ones we buy in the grocery store that are grown in California are English walnuts (Juglans regia) which would not be possible without the life-giving participation of black walnut trees (Julgans nigra).
Non-native English walnuts are susceptible to root diseases in California so walnut farmers plant native black walnut trees to start the orchard. When the black walnuts are a year old with strong roots and vigorous base they are chopped off and an English walnut shoot is grafted to the stump.
All the trees in the orchard below show the wider stump base (highlighted in yellow) that ends at the graft point. Above the graft English walnuts produce their own delicious nuts which are harvested after they fall by sweeping and vacuuming from the ground. FLORY harvesting equipment is pictured below.
Black walnut trees can be identified in winter as a bare tree standing alone with twigs that have alternate (not opposite) small buds above large leaf scars.
Black walnut trees stand alone because …
Like other walnuts, the roots, inner bark, nut husks, and leaves [of Julgans nigra] contain a nontoxic chemical called hydrojuglone; when exposed to air or soil compounds it is oxidized into juglone that is biologically active and acts as a respiratory inhibitor to some plants. Juglone is poorly soluble in water and does not move far in the soil and will stay most concentrated in the soil directly beneath the tree.
Symptoms of juglone poisoning include foliar yellowing and wilting. A number of plants are particularly sensitive. Apples, tomatoes, pines, and birch are poisoned by juglone, and as a precaution, should not be planted in proximity to a black walnut.
Different species of hickory nuts look the same … but not quite. This one, partially in its husk, was a puzzle so I brought it home. Husks and shells together provide the clues so I had three nuts to work with in various stages of undress, plus a table of southwestern PA hickory husk and shell characteristics.
Characteristics of Southwestern PA Hickory Husks and Shells
Very thin rough husk with 4 wings, splits only to the middle as if it is peeling off the shell
Nut is round, small and thin-shelled with a pointed tip
The Verdict: The photo was taken after the nuts sat indoors for three weeks. The husk is still pear shaped but has turned brown and splits completely. Hmmm. The nut, however, has no ribs so I’d say this is a pignut.
Sliced open it would look like this. I lack the tools to make such a clean cut.
Pignut hickories (Carya glabra) range along the east coast (the original colonies) all the way to the Mississippi Valley and down to the Gulf of Mexico but don’t normally grow in northern Pennsylvania.
In winter they are best identified by their buds. As with all hickories, the end bud is larger than the side buds but on the pignut it is relatively small and the side buds are almost at right angles to the twig. This one is about to burst into spring leaves.
Young trees have smooth bark. Mature ones have these ridges.
The tree’s compound leaves have 5-7 serrated leaflets …
… which turn a beautiful golden color in the fall.
But now the trees are bare.
Bonus! Did you notice the clean hole in the center nut in my three-nut photo? It was probably made by a pecan weevil (Curculio caryae). The weevil drills a hole to lay its eggs inside developing hickory nuts, including pecans.
How does she drill into the nuts? Check out this video of acorn weevils drilling and mating.
Nowadays it’s rare to write anything by hand unless it’s the size of a Post-It note. When we really want to say something we use keyboards and touch screens to generate digital text read on screens or, less often, on paper. Our writing equipment becomes obsolete so rapidly that our computers and cellphones are replaced within a decade. (Who among us is still using the same cellphone since 2013? Do we even remember what model it was?)
So consider this: Humans used the same writing tool, the same indelible ink, from the 5th to the 19th century. When applied to parchment, it is readable 1,700 years later. The ink is easy to make by hand from natural ingredients and is still used in calligraphy today. To make iron gall ink, the process starts with a wasp and an oak.
Two more ingredients transform the ink for final use: Iron sulfate dissolved in water makes the ink black.
Gum arabic dissolved in water makes the ink sticky enough to hold onto parchment or paper.
This video from the British Library shows how iron gall ink is made.
Eventually we used paper instead of parchment, even for important documents, and iron gall ink fell out of favor because the acid in iron sulfate makes the paper disintegrate. To solve that problem we invented paper-friendly inks and then computers.
Medieval manuscript creation used natural products from animals, plants and minerals. See the process from parchment to ink to binding in this 6-minute video from the Getty Museum.
Songbird migration is quiet now and birds, when they’re found, are in mixed species flocks.
On 7 November, Charity Kheshgi and I encountered agitated golden-crowned kinglets, tufted titmice and dark-eyed juncos but it took us a while to find what they were upset about. This red morph screech-owl was hiding above our heads in a small oak.
An exception to the mixed species flocking rule is our “murder” of crows. My guess is that Pittsburgh’s winter crow flock is 90% American and 10% fish crows, but who can tell? They look alike.
In late afternoon crows stage in the trees in Shadyside and Squirrel Hill, then head west at sunset. 6,000 to 10,000 pass by my building on their way to the roost.
At sunset black birds in a darkened sky are impossible to photograph but it’s another story at sunrise. Click on the photo below for a closeup of crows in the brightening sky.
Leaves littered the ground this week and the air was filled with the sound of leaf blowers. 🙁
Most of the trees were bare in Schenley Park by Friday 10 November.
And finally, a reminder that the rut is still in progress and deer are crossing roads. This duo showed up at a Squirrel Hill polling place on Election Day at a place surrounded by roads. So watch out.
Though their names differ by only one letter bitternuts and butternuts are not the same at all.
Bitternut hickory (Carya cordiformis) is one of the most common hickories in southwestern Pennsylvania and easy to identify by its slender sulfur-yellow buds.
Bitternuts are closely related to pecans and also share the hickory genus with shagbark hickories, pignuts and mockernuts. Unlike the pecan the bitternut tree is rarely cultivated.
The fruit is a very bitter nut, 2–3 cm (0.75 – 1.25 in) long with a green four-valved cover which splits off at maturity in the fall, and a hard, bony shell.
The “green four-valved cover” turns brown after the nut lies around for a while (see middle nut at top) and indeed the shell is hard and bony. I had to use a hammer to open this one and damaged the perfect nutmeat in the process. You’ll have to imagine it was shaped like a short squat pecan.
I can tell you from taste-testing that the nut is bitter and astringent. Squirrels avoid these nuts though Wikipedia says that rabbits eat them.
Butternuts (Juglans cinerea), on the other hand, are prized because the nuts taste good.
Butternuts are in the same genus as black walnuts and sometimes called “white walnuts.” The leaf arrangement is so similar that I didn’t realize that I was looking up at a butternut tree — to see warblers — until I saw the nuts on the ground.
Notice how similar the husks are: butternut on the left, black walnut on the right below. The butternut husk is oblong and fuzzy.
As the husk deteriorates (at left) the lumpy nutshell is revealed.
A cross section of the nut shows the rough exterior and nutmeat inside.
The butternut’s natural range runs from Maine and southern Ontario to southeastern Missouri and is smaller than the bitternut hickory’s. While the bitternut thrives, the butternut is declining and listed as threatened in some U.S. states and endangered in Canada. Its biggest threat is a fatal disease, butternut canker, caused by a fungus imported with the Japanese walnut. Ironically butternuts are partly threatened by too-easy hybridization with Japanese walnut trees.
Like black walnuts, butternuts are shade intolerant and thrive only when they’re at the top of the canopy or in an open space. Now that I know what a butternut looks like, I’ll pay more attention.
If you find a small spiny capsule on the forest floor that opens to reveal two to three nuts (in this case two are nicely packed together) you’ve found beechnuts. Without even looking up you can be sure you’re near an American beech (Fagus grandifolia).
The fruit [of Fagus grandifolia] is a triangle-shaped shell containing 2–3 nuts inside, but many of them do not fill in, especially on solitary trees. Beech nuts are sweet and nutritious, can be eaten raw by wildlife and humans, or can be cooked. They can also be roasted and ground into a coffee substitute.
Beechnuts can be eaten raw? Well, it’s complicated. Foraging Beech Nuts explains that it’s best to let the capsules dry out for 2-3 weeks and then cook the nuts because some people get throat irritation from the raw seed coating.
In Pittsburgh’s parks beechnuts can be hard to find because they are so popular with deer and squirrels. Looking for a beech without looking up? Here’s another clue.
Beech drops (Epifagus virginiana) are parasitic on beech tree roots so if you see these well camouflaged plants you are definitely near an American beech. Read about them at On The Beech.
Looking up at American beech trees this month you’ll see brown beech leaves clinging to the branches.
Its buds are distinctive: long, pointed and golden brown like its fall leaves.
The trunk has smooth gray bark.
And at the end of winter, small American beeches have pale, rattling leaves that make them stand out in the forest.
All the beechnuts will be eaten or hidden by the end of winter.
p.s. If you’re my age you probably remember Beech-Nut chewing gum. Were there beech nuts in it? No, that was the name of the company. The gum’s claim to fame was its peppery peppermint zing.
Whatever happened to the candy? The candy division of Beech-Nut went defunct in 1976. Read about the Beech-Nut company here.