r/botany • u/Highmountainbotany • Jun 03 '23
Physiology Question: Purple Locust flower Mystery
This year something strange is happening to the locust trees around my town. We had record winter with the amount of snow and cold temperatures (this is in Northern Nevada) and many of the purple robe locust trees that have been purple for the last 10-20 years have bloomed white flowers instead of purple for the first time ever. I know that the black locust graft they use for these trees have white flowers, and runners of the root stock will sprout up white but none of these purple robes died back, they simply just have white flowers this year instead of the normal deep purple. At first I thought it was a one off, but it’s happening to a bunch of the trees here now. I’ve never really heard of something like this, and I can’t find any information about it on google. What sort of mechanism would have caused this reversion?
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u/No-Union-7227 Jun 19 '25
I came here looking for an answer to why my purple robe locast is flowering white this year after purple in the past. But it sounds like it's a mystery! In northern Michigan.
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u/Highmountainbotany Jun 22 '25
Crazy right? And I’m sure there’s an explanation out there. Just as we speculated two years ago, most of the trees (at least the ones I went back to at the clients that hired me originally) turned back to their regular purple the following season, they were purple this season as well. I looked a little more into genetic flower reversion like others said but it’s not really documented well enough in events like this for real data to come through. So still a mystery for now.
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Jun 03 '23
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u/Highmountainbotany Jun 03 '23
At first I thought people were mistaking it for one of the suckers and I didn’t believe it until I saw it with my own eyes. I’m at a loss.
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u/[deleted] Jun 03 '23
Definitely sounds like a stress response. Cultivars often “revert” to more vigorous, “normal” growth patterns when they face environmental challenges. Plants often have multiple genes coding for similar growth and the stress triggers genes that are typically dormant to create hardier growth patterns. That’s whats happening when you’ see variegated plants with one or more fully green branches, though sometimes reversions happen at random. It will be interesting to see if this is a one time event or if the trees only bloom white from here on.