Aspen Galls

I promised you a little winter tree ID. Well, clumps of these young trees grow along our trails in abundance, particularly in fairly open areas. Know what they are?

Okay, I kind of gave it away with the title of the post – these are young quaking aspen, Populus tremuloides. Even when they’re this young, their smooth, pale bark and tendency to grow in clusters (the form “clonal colonies,” with many trunks growing from the same set of roots) give them away. They’re an early-successional species, meaning they’re one of the first trees to grow back in an area that’s been disturbed. Another thing to look for is pointy reddish buds. On the trees here, many of the buds have swollen, almost bubbly-looking areas at their bases.

These are galls, caused by a fly called the poplar twiggall fly laying its eggs at the bases of the buds. They’re generally not harmful to the tree.

Do you have aspens where you are? In the fall their leaves turn a beautiful golden color, and as far as I’m concerned they’re one of the most beautiful trees in the North Woods.

11 thoughts on “Aspen Galls”

  1. How amazing that there are fly eggs are inside the gall. They really are gorgeous trees, especially when lighting up the forest in the fall. Look at all that snow, it’s heartening to see that you are having a “real” winter up there!

    1. Aren’t you just as “up there” as I am, being in Ontario? Don’t tell me even CANADA is lacking in snow this winter?? Oh dear. Actually we did have a bit of a thaw this past week but we had so much snow on the ground beforehand that most of it’s still there.

  2. Not to many Aspens here on Cape Cod, MA. We have had a real problem with Oak Galls however! Their number have been increasing and causing a good bit of damage to the local Oak population in recent years.

    1. I remember lots of galls on the leaves of the Live Oak when I worked in Georgia – I don’t suppose that’s the kind fo oak you have in Mass., though. Luckily the aspen galls don’t seem to be too harmful to the trees. (The cherry trees are a different story… I swear, every single cherry tree on this property is infected with black knot fungus.)

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