What the heck is going on with this tree?

March 29, 2018 5:49 PM

I saw this tree while surveying a roof in Northeastern Massachusetts this week. As best as I can tell, it is an ash tree on the bottom and a birch tree on top. This makes no sense to me. What is the deal with this tree?

In case it's not obvious from the rather crappy picture, the bottom half of the tree is heavily corrugated, not merely striped. The corrugations have that X-type pattern that I associate with white or green ash (at least to my eye) while the top half of the tree is very obviously a paper birch.

It doesn't seem likely that this is a hybrid, as birch and ash are not particularly closely related; the most you can say is that they're both eudicots, but birches are rosids while ashes are asterids—a major division within the world of flowering plants. Also, if it were a hybrid, I would expect to see a mixture of ash-like and birch-like characteristics across the whole tree, rather than all ash on the bottom and all birch on top.

The bark at the bottom half is like nothing I've ever seen on a birch tree. As you can see if you browse through my Instagram history, I've made something of a study of the variation in birch bark over the last year or so. (If you're looking, look way back to last winter because that's when I posted birch bark most frequently.) I've seen a lot of bark that deviates from the traditional whiteness of paper birch, but I've never seen this kind of grayish-brown corrugation. Or rather I've seen it, but on ash trees.

So, hivemind, what is the deal? Who can tell me what is going on with this tree?

posted by Anticipation Of A New Lover's Arrival, The to Science & Nature (7 answers total)

Is it possible it's an aspen? They can look a lot like a birch from a distance, but their bark varies in texture -- see here for an example. Or just image search for "aspen bark".
posted by irrelephant at 6:09 PM on March 29, 2018

Welp, got it in one. Shows what I know! Thank you so much. Now I need to educate myself about how to tell the difference between American aspen and paper birch.
posted by Anticipation Of A New Lover's Arrival, The at 6:15 PM on March 29, 2018

I think it's a poplar or aspen. Compare these pictures of Populus alba or these of Populus grandidentata.
posted by Redstart at 6:17 PM on March 29, 2018

For posterity, if anyone cares, the bark of American aspen is less "peeley" than paper birch, and it has more "eyes" and fewer lines. Also sometimes it gets all brown and wrinkly. The more you know! 💫
posted by Anticipation Of A New Lover's Arrival, The at 7:12 PM on March 29, 2018

This is a birch. The change in bark texture and thickness is the result of time and weather and the particular cultivar. Many trees have bark that changes as the tree gets older. Since birches tend not to be long lived, it may be that you have not often had a chance to run across one as old as this beautiful specimen.
posted by eleslie at 4:21 AM on March 30, 2018

Elselie, it was maybe only 10" dbh. I know where there's a paper birch in New Hampshire that's easily 30" dbh. I'm a little bit of a birch bark connosieur, and I've seen and photographed a lot of majestic, heavily-weathered birches. I've seen them get scaly for sure, that does often happen to older birches. I've never seen them get corrugated though—that's why this one jumped out at me. But apparently that is a thing that aspen sometimes do, and also while they normally have bark that looks quite similar to birch, it's smooth and unbroken—which matches the look of the upper parts of this tree.

So I remain pretty confident that irrelephant's answer is correct, though if you have additional evidence for the weathered birch theory I'm here for it!
posted by Anticipation Of A New Lover's Arrival, The at 12:57 PM on March 30, 2018

No it's definitely a poplar of some kind.
posted by ArgentCorvid at 7:36 PM on March 30, 2018