Stem Research (or, Why Does My Campanula Look So Weird?)

As much of a Marvel Universe fan as I am, that doesn’t mean I’m necessarily prepared for a strange mutant to pop up unexpectedly in my planting bed. The next logical question is, what – if anything – should I do about it?

Among the plants I ordered from Bluestone Perennials in May 2020 were four Campanula persicifolia ‘Alba.’ They arrived in their usual annoying (to me; yes, I’m a grouch) 3.5” coir-fiber pots, from which they were removed upon planting in my mostly-white-flowers full-sun front walkway bed. They remained there for about a month and were then relocated across the walkway to the all-white border after a group of daylilies were evicted relocated after their color didn’t pass muster.

None of the campanulas flowered last year, but they did make healthy tufts of foliage. This was taken in June 2020, a few days after they were moved to the other bed, in front of the two hosta ‘Half and Half.’

I was surprised but pleased to see that the campanulas remained green and healthy all winter, despite (or perhaps because of?) being buried under at least a foot of snow for most of that season. In April I noticed the beginning of flower spikes which began to elongate and sway gracefully in the breeze….

…except for one of them, whose stems more closely resemble a 2×4 than a graceful anything. Or, to be fair, a wide flat ribbon. This view is from behind the campanula group.

The flower buds are crowded together at the top, and the leaves poke out of the fused stem/ribbon like soft spikes.

 

The plant has also produced a second, shorter group of fused stems as well.

This fusing together of normally-separate plant parts is called fasciation. There are several possible causes but the prevailing scientific opinion is that it’s the result of a hormonal imbalance. Such an imbalance can be caused by a genetic mutation, or by a bacterial or fungal infection, or even physical trauma.  There is a specific bacterium, Rhodococcus fascians, shown to cause fasciation in certain plant species but it doesn’t seem to be universal. Some scientists believe that exposure to chemicals might also be a contributing factor.

There also seems to be a divergence of opinion as to whether fasciation can spread to other plants. Most say no, but are unclear as to whether that means plants of the same, or of different, genera. However, others say that if the fasciation is caused by a bacteria, it could indeed transfer to adjacent plants either through the soil or by insect activity. Sometimes fasciation recurs again in the affected plant, but sometimes it doesn’t.

As far as my ‘ribboned’ campanula is concerned, I think the cause is most likely hormonal/genetic. Why? Because the overall foliage color of this plant is a darker green than the other three. Now, this may be because it’s also the rearmost one of the four, and thus is the first one to become shaded each afternoon (this bed gets sun from dawn to about 2 pm), but looking at that June 2020 photo I can see that this plant was a darker green even then. The fasciated plant’s basal leaves area also larger and thicker. So my guess is that whatever imbalance/mutation/whatever has caused the fasciation, also affects the foliage color and substance as well.

So, what will I do with this unexpected mutant creature? Although it’s a curiosity, frankly it’s not one that appeals to me and I certainly don’t want any of the other campanulas to exhibit this trait. I’m leaning strongly toward allowing a few of the flowers to open, just to see how they look, and then removing the plant so that there’s no risk of it spreading, either physically or genetically. And, given the natural tendency of the peach-leaved bellflower to grab new territory, I’m sure the remaining three plants will be quick to fill the gap!