Naturalist’s Corner - A Black Locust Super Bloom?

Have you noticed the sudden appearance of clusters of white trees in the usual greens of the Driftless bluffs? What’s up? That’s what I said too. I can't recall seeing this phenom in black locust trees other years. Why the sudden proliferation of blossoms? Derrick Mayoleth to the rescue! He wrote an informative post on his Skillet Creek Media Facebook page about what’s up with this very subject. Derrick writes (and photographs and films) extensively on the Dells and Baraboo Hills area of WI where the Driftless area ends and both moraines and unglaciated geological formations tower.  He explores and celebrates the incredible landscapes, trails, parks and opportunities and loves connecting people with nature via education, respectful discussion and inspiring visuals of Wisconsin's beauty. You can also find him at Skillet Creek Photography.  This column is reprinted with permission from his June 2, 2025 Skillet Creek Media Facebook post.

Image - Skillet Creek Media

A Forest Super Bloom?

I’ve heard a lot of comments recently about the white trees everywhere. We’ve all seen plenty of white-flowering trees around Wisconsin, but this year feels different. Some folks are concerned when they see clumps of white trees in the distance. Others are just curious.

You may have seen my story post yesterday, where I said these little islands of white on the hills look just like Minecraft’s Creaking Forest. And honestly, they do. 😉

What we’re seeing could almost be called a “superbloom” of black locust trees. And if you were concerned, you’re not wrong to be. But maybe the reason isn’t what you thought.

Black locust trees are invasive here in Wisconsin. Once established, they can invade forests, upland prairies, old pastures, and roadsides. They spread aggressively by cloning themselves in tight clusters, suckering out from underground roots. In fact, if their roots are damaged, they often spread even faster.

The Wisconsin DNR tells us that neither cutting nor girdling is effective on its own. Burning and mowing can temporarily slow the spread, but long-term, those methods can actually make things worse. I’ll drop a couple of links in the comments if you want to learn more about control efforts.

So why are they standing out so much this year?

Black locust blossoms
Image -Marge Loch-Wouters

Well, the spring weather has been perfect for them. When black locusts get just the right mix of sun and rain, and dodge any late-season frost, they can go a little wild. This seems to be one of those years.

On the upside, their pea-like flowers are beautiful. Black locust blossoms have a sweet, floral scent, often compared to a mix of orange blossom, honey, grape candy, and freshly cut hay. The fragrance really kicks in on warm, humid days.

So no, our forests aren’t dying. But they are being quietly invaded by a showy, fragrant outsider. How’s that for mixed messaging?

Additional Resources:

About Invasive Black Locust - https://dnr.wisconsin.gov/topic/Invasives/fact/BlackLocust

More from the US Forest Service - https://www.fs.usda.gov/wildflowers/plant-of-the-week/Robinia-pseudoacacia.shtml

It’s a white-out!
Image - Marge Loch-Wouters