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.

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.

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)

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.

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)

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.

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)

26 July 2021

Two trees in the Birch family (Betulaceae) are common in the Pittsburgh area but I’ve struggled with what to call them because they have the same names.

Both are called Ironwood because their wood is hard, close-grained, and very strong. Ironwood is a poor name choice, though. About 160 species around the world are called “ironwood”.

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).
• American hophornbeam fruit looks like hops, hence its name (right below). Click here to see what hops look like.

Both species with fruit and bark paired.

They differ by a hop.

p.s. Because of their similar names I sometimes call “hornbeam” by another common name: blue beech. More confusion!

(photos by Kate St. John)

13 July 2021

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.”

In Wisconsin box elder is so disdained that the Urban Ecology Center wrote a blog in defense of it: Native Tree Spotlight: In Defense of Box Elder.

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.

p.p.s. Did you know there’s a Box Elder County in Utah named for the abundant trees?

(photo at top by Tom DeGomez, University of Arizona, Bugwood.org, remaining photos by Kate St. John and John English)