I’m almost ready to blame this freaky mutant on fallout from the Fukushima Daiichi reactor disaster.

On my way to the office, several times a week, I walk past a cultivated patch of Hooker’s evening primrose, Oenothera elata. A few days ago I noticed this mutant crested growth on the central growing point on one of the plants. I’ve noticed this crested growth pattern in the garden a few times, most recently on a euphorbia. But this is the first time I’ve noticed it on a primrose–or any other local native plant for that matter.

In a case of crested growth, the growing tip on a stem, the apical meristem, changes from a single growth point to a growth all along a broad line of cells. As the cells along the line grow, the plant forms a fan-shaped growth instead of a slender stem.

In this second photo you can see a normal stem to the right for comparison: slender normal stem, big fat mutant stem.

And here you can see the crested stem from the side and how it widens as it rises.

Pretty weird, huh?

A trip to a cactus show or nursery site for succulents will likely turn up a section devoted to plants with crested (or “cristate”) and monstrose growths. Generally I find that the shapes of plants are interesting enough, and I usually don’t go gaga over some genetic oddball.

But the oddball cresting behavior found its way to the garden anyway. This is a young Euphorbia lambii in the back yard, one of four I have growing in pots.

Here’s a closeup…

And here’s a view from the top…

The typical habit for this plant is to produce branches that are distributed around its growing tip, something that you can see in this normal lambii nearby. With the crested mutation, the apical meristem, the point where new growth emerges, has changed from a point to a line. So instead of a cylindrical stem with branches all around, you get a stem that grows flat, like a cobra’s hood, with new growths distributed along that line.

From what research I’ve done it isn’t apparent what causes this particular mutation. The genus Euphorbia, however, is one of those where you could encounter it fairly commonly. (If there’s anything in the plant’s environment that caused it, I wonder if might be drought stress. Of the four plants, this one received the least amount of water. A couple times it came close to defoliating. All the others are growing normally.)

I’ll admit that the crested growth interesting. Maybe I’ll learn to love it. But I’m not there yet…