The effect of leaf shape and posture on water direction

I have this avocado tree that I started from seed on a lark. Usually the chipmunks destroy them, but this one made it. It's in a pot because Minnesota, right? Anyway, the pot is too small and I need to up-plant it and we haven't been getting rain, so it's wilty just now and I moved it so that it was in the blast of a sprinkler that's really there to serve more important plants. But I watched the water from the sprinkler nailing the leaves and it made me think. When the leaves are wilty, they're pointing straight down and the water was hitting the leaves and running right down into the central root zone. In a while, it'll perk up and the leaves will be pointing more outward and it'll act differently. That's pretty cool.

This is something that botanists must study, but I haven't ever thought much of beyond the realization that leaves interact with rain and funnel water to where the tree needs it, in a very general sense. Anyone out there have any cool observations or learning in this domain?

I'm going to stick a couple of links here, as much as anything so that I come back and read them when I have more time, but also because y'all might be interested:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8866647/
https://academic.oup.com/jxb/article/73/4/1176/6417382
https://academic.oup.com/jxb/article/70/14/3549/5442601

Hi Chris. Great link (the second one, first is currently broken). I’ve had a similar thought. Different plants prefer to get water different ways, and I’ve oftentimes observed the shape of the leaves to see if it channels water directly to the crown or outwards to the spreading roots.

/D

When leaves are pointing down and looking sad they are always telling me the leaves are thirsty.

I don't know if how I water them makes any difference.

Anne Miller wrote:I don't know if how I water them makes any difference.

My first thought was that that's almost exactly my point -- you don't really need to alter your watering practices because the tree is taking care of it thus: At least when the tree is quite small, if the leaves point down, they direct the water to fall near the trunk. But when they stiffen up, they direct the water to the edge. It might be that the central roots need the water to mitigate the emergency shortage, but otherwise, it wants water at the dripline to facilitate new root growth...or something like that.

But actually, maybe we can learn from it. The lesson I'm thinking of is that a static watering solution like drip-tape might sometimes be delivering the water to the right spot, but other times failing to do so -- and the tree has no power to fix things because our technology is too precise. But if we're overhead watering (wastefully), then the tree's inbuilt systems are going to put the water where it needs it. And maybe that drip-tape isn't really a problem if you're super-attentive and always moving it to the right place, but if not, letting the plant see to its own needs might make more sense.

My thinking…,you can rarely go wrong watering the roots. One can often go wrong with overhead watering.

Daniel Ackerman wrote:One can often go wrong with overhead watering.

People say that, but it's hard to imagine that nature got it so wrong...

There are plenty of places in the world that get very little overhead irrigation, in favor of flooded stream banks or the like.  Roses come from one of these places, for example, and do better without so much water on the leaves.  Nature took care of them just fine where they came from, and it's up to us to adjust if we establish them elsewhere.

I actually wonder more about how the leaf-directed water diverts irrigation when the roots are confined in a pot.  If a plant's natural leaf shape would direct it out to the root tips, but that's far beyond the size of the pot, does overhead watering not get very much to the roots?  Will a plant adjust this for being in a pot?  Sometimes I wonder on these things.

I don’t have a lot of potted plants, but for those that I do have, i generally water the soil rather than the foliage. Unless I give my begonia a shower, which it likes.

It look like a unique natural response that I hadn’t fully considered before. But plants have evolved ways to maximize water intake in challenging conditions. Nature’s efficiency!

Yep!!