Why are my Iris leaves pleated?

Yes, you read that correctly - pleated!

Here are some emerging Iris leaves, and this is from a fortnight ago,  so we're talking late February, which is end-of-winter heading into early-spring.

Several of the leaves showed this strange accordion pleating.

Not all of them, just a few of them.

Weird, huh?

I did some internet research, and there was a not of information on the subject: but when I consulted my fellow self-employed gardeners, quite a few of them had observed this phenomenon.

But no-one really knew what causes it.

My initial assumption was that the leaf had become temporarily trapped, while emerging: I find this sometimes, on roses and on peonies: if we've had some wet weather, the outer layers can become mushy, then they dry to form a papier-mache skin, which prevents the flower from opening.

Sometimes, if you catch it early enough, and pull the outer layers off, then the flower will open normally: but sometimes the whole bud rots inside the papery outer layer, and is ruined. Ruined! (*laughs*)  (and if you are wondering why that makes me laugh, it's because I always say the second "ruined" in the style of Kenneth Williams.)

So when I saw these pleated leaves, I assumed it might be something similar - but of course, as soon as I thought about it, I realised that no, it can't be that, otherwise it would be the tip of the leaf which was pleated, not the middle section.

Some of my fellow gardeners thought it was do with water - either too much of it, or not enough of it, at a critical point of development.

Some others thought it was to do with temperature changes, and I did find one reference on the internet to this being caused by a sudden onset of hot dry weather: but the site in question was not a scientific site, and - bearing in mind that it's mid February - I don't really think that we've had any hot weather lately!

The pleated leaves don't seem to be harmed in any way other than cosmetically: they are still green, they are photosynthesising, they just look a bit weird. I suppose I would suggest that, if these leaves are not pleasing to your eye, just cut them out at the base and don't worry about them.

This means that my answer to the question "Why are my Iris leaves pleated?" is "I'm afraid I don't know!"

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