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)
Their scientific names are different but their default common names are very similar: American hornbeam (Carpinus caroliniana) and American hophornbeam (Ostrya virginiana). Hornbeam refers to their hard, strong wood: horn (hard, bony structure) + beam (Old English for tree). Hop is the only difference.
Fortunately they are easy to tell apart in the field at any time of year. In the photo at top:
The bark of American hornbeam looks like sinewy muscles (top left).
American hophornbeam bark peels in narrow parallel strips (top right).
Both trees produce fruit enclosed in an involucre, a whorl or rosette of bracts surrounding the inflorescence. This is where “hop” comes in.
The fruit of American hornbeam looks like a drooping whirligig (left below).
In Pittsburgh we hardly think about box elder (Acer negundo). It’s a native tree that grows by the river. No one plants it. It’s not a “bad” tree. So I was puzzled by this 1950’s story from my mother.
I never hear of box elder that I don’t think of your grandfather. He never had a bad word to say about anyone. He was a man of integrity and the absolute worst thing I ever heard him say was [this] about a member of the town council: “He was the kind of man who would plant box elder.”
— 1950’s family anecdote from my mother
My grandfather lived in a village in suburban Chicago in the heart of the Midwest where box elder is considered bad, ugly, weedy and invasive. Wikipedia provides this insight on how it got a bad reputation:
“After World War II, box elder’s rapid growth made it a popular landscaping tree in suburban housing developments despite its poor form, vulnerability to storm damage, and tendency to attract large numbers of box elder bugs. … It can quickly colonize both cultivated and uncultivated areas. … It grows around houses and in hedges, as well as on disturbed ground and vacant lots.”
Box elder isn’t invasive in Pittsburgh so I had to go look for it on its home turf at Duck Hollow. There I found that as a shade tree it can look pretty good. This one is two box elder trunks intertwined.
However some of them die back leaving ugly bare branches at the top.
And if you cut box elder or chop it down it grows suckers from every crevice.
Midwesterners agree that box elder is bad. Why don’t Pittsburghers have this aversion? I think it’s because we are on the eastern edge of box elder’s range, we never planted it as a street tree, and it isn’t particularly invasive here.
What is invasive here? Japanese knotweed! Originally planted as an ornamental, we don’t think it’s pretty anymore.
If my grandfather had lived in Pittsburgh perhaps he would have said “He was the kind of man who would plant Japanese knotweed.”
Aha. Now I get it.
p.s. Later this summer box elder bugs will appear though not in huge numbers at Duck Hollow.
The air smells honey-sweet in Pittsburgh this month because the basswoods (lindens) are in bloom.
American basswood (Tilia americana) is a native tree in eastern North America with close relatives across the Northern Hemisphere. In Europe Tilia species are called linden trees. In the British Isles they are “lime trees” though not at all related to lime fruit. (Aha! Lindens are the “avenue of lime trees” in English novels.)
Basswoods grow naturally in the forest (left below) but are often used in landscaping. You can recognize them by their large size and distinctive teardrop shape (right below).
In June you can find them by smell, which is how I discovered the basswood at top in Schenley Park on 12 June.
Bees find them, too, so here’s a word to the wise. Never ever spray pesticide on linden (basswood) trees in bloom. A pesticide company did that in Oregon in June 2013 and killed 50,000 bees, the largest native bee kill on record.
We are usually unaware of wild honeybee hives high in the forest and that was certainly true of this one near the Westinghouse Shelter in Schenley Park. The bee tree broke during last Sunday’s storm and just missed hitting the shelter. At noon on Tuesday I found the tree cordoned off by Public Works as they waited for the bees to be removed.
The massive hive was in a hollow 20+ feet up in a red oak. When a northwest gust hit the tree it broke at its weakest point and split the hive. Most of the hive remained in the upper section with a few empty honeycombs in the dangling piece.
Rather than step closer I zoomed my cellphone camera to show the bees covering the hive (center of photo) and more honeycombs at top right in the hollow.
When I passed through at 1:30pm, beekeeper and DPW Schenley Park worker Kevin Wilford was carefully moving the hive to a bee transport box. He attached the white box to the tree to encourage the bees to go in it after he moved the hive. However, the hive was so deep that he could not reach it without more tools. The process took longer than I had time to watch but Kevin gave me a taste of it, a small piece of honeycomb laden with honey. Mmmmmm good! and sticky!
By Friday the beehive will be on a scenic hill above Hazelwood, the damaged tree will be gone, and the Westinghouse Shelter will be ready for use.
UPDATE on 24 JUNE 2021: As I passed by the bee tree today I could see that most of the hive was still in place. The bees are very deep inside the hollow so the tree is still down.
UPDATE on 1 JULY 2021: The end of the bee tree. It is gone except for a very tall stump.
At 6pm on Sunday evening a violent thunderstorm blew through Pittsburgh with powerful wind gusts, hail and heavy rain.
Dave DiCello photographed the storm from the West End as it approached Oakland. The VA Hospital and the Cathedral of Learning are to the right of the lightning bolt.
Watching that storm roll into #Pittsburgh today was incredible. A huge hail core, tons of lightning; looked like the apocalypse coming into town. Though this wasn't the largest bolt I captured tonight, it is my favorite image. An absolute monster of a cloud. Lots more to come. pic.twitter.com/b6aqMnbPNZ
Meanwhile my husband and I watched from our 6th floor apartment as a wind gust picked up the patio umbrella from the high-rise roof next door and blew it, Mary Poppins-like, until it crashed into our building. Then we saw no more as rain and hail battered our windows for half an hour, first from the north, then the east.
The tempest left behind flooding, downed trees, power outages, and a rainbow.
Yesterday morning I surveyed the damage after the cleanup had already begun. In a short walk I found trees down at Frick Fine Arts, Carnegie Library and Museum, and two small breaks on South Craig Street.
At Schenley Park the valley around Panther Hollow Lake was spared but the lake itself was full of flood water. This is by design. A flow control gate at the outlet holds back freshwater so that storms will not flood The Run.
This morning the power was still out in parts of Squirrel Hill as I drove home from the grocery store.
My husband and I were fortunate. Our power never failed and that flying umbrella hit the wall below us and caused no damage.
p.s. The young Pitt peregrines are flying so well that they are hard to find. I saw both adults plus two of four juveniles on my Monday morning walk.
Have you ever seen these long black ropes draped on a fallen log? They were hidden under the bark before the tree died, and they’re the reason the tree died. These are mycelial cords or rhizomorphs of Armillaria, a genus of fungi that ultimately kills trees. It attacks the trees from underground.
Instead, Armillaria spreads by the rhizomorphs shown at top which travel only eight inches below the soil surface, advancing about 3.3 ft (1 m) per year. As they make contact with another tree they invade the roots and then the trunk. If a tree is already infected it will spread the fungus via root grafts.
Yellow-bellied sapsuckers (Sphyrapicus varius) leave behind evidence of their visit when they pass through Pittsburgh on migration. In their search for food sapsuckers drill horizontal rows of holes on tree trunks and large branches, then lick the leaking sap and eat the insects attracted to it.
The trees cope as best they can with this unusual damage. Shagbark hickories (Carya ovata) grow puckered bark around the holes.
This week Pittsburgh’s sugar maples are clothed in spring green flowers while the oaks remain bare. Most trees bloom long before leaf out so their leaves won’t block the pollinators. These flowers take full advantage of the wind.
Did your allergies kick in this week? The trees are throwing off lots of pollen with little rain to lay the dust.
Insect-pollinated flowers will follow soon. On 3 April pawpaw flowers (Asimina triloba) were still tiny buds in Schenley Park but by the time they bloom the stems will be long and flexible. The dark maroon fetid-smelling flowers will hang like bells to attract flies and beetles. Click here to see a pawpaw flower.
Eastern redbud flowers (Cercis canadensis) had not opened in Schenley as of 7 April, but they showed promise.
Spring cress (Cardamine bulbosa) was blooming at Raccoon Wildflower Reserve on Easter Day.
This winter I noticed that when moss grows up the base of saplings it looks like leggings on the trees. At Raccoon Wildflower Reserve I found an entire group of saplings wearing mossy leggings. Click here to see the whole group. (Anyone know what this mossy phenomenon is?)
Spring green will continue in the coming weeks as tiny leaves pop open and more trees bloom.
Flowers are pushing up their leaves and sap is rising in the trees.
On Friday the sap was rising so fast in this fallen red oak that it was dripping to the ground. The oak keeled over last year in Schenley Park leaving just one root in the ground. That root is still doing its job.
With temperatures this week above freezing during the day and below freezing at night I imagine it’s still maple sugaring time in the Laurel Highlands. Sugaring ends when the buds open. They haven’t opened yet in Schenley Park (below).
Other trees have swelling buds.
Below, silver maple (Acer saccharinum) buds were about to burst when a squirrel gnawed the stems and they fell to the ground. Do squirrels nip off the buds to get to the sap?
Meanwhile daffodil leaves are turning green in Schenley Park.
Tulip leaves emerged on a busy street in Oakland where the deer can’t get them. 🙂
And there is mud.
The snow melted all at once last weekend and the Monongahela River rose high, flooding the Mon Wharf. On Wednesday 3 March it was sunny and 60 degrees, a great time for a walk … but not here!
When the river receded it left behind leafy debris and deep chocolate-pudding-like mud at South Side Riverfront Park. I tried to walk down there but I gave up before getting muddy. Others were not so careful. You can see deep footprints in the shade in the photo above (bottom left).