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Peace Lily Question

Posted by plantomaniac08 8a (My Page) on
Tue, Jun 19, 12 at 22:34

I was repotting my peace lily earlier today and accidently broke off one of its newest leaves (it just opened a week or two ago). I left the remaining part of the stem on the plant. Perhaps this is a silly question, but I would like to know if it will it create new leaves to replace the one I broke off or will this cause it to stop growing altogether? Thanks in advance, probably my plant paranoia kicking in but I wanted to ask anyways. :)

Planto


Follow-Up Postings:

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RE: Peace Lily Question

Planto, I'm afraid not. Once a leaf is damaged, it's gone. New growth will not grow on the stem. In fact, you might as well cut the leafless stem closest to the soil line.

The good news is, your PL will continue growing. More leaves will sprout.

We all have a little paranoia in us, lol, Toni


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RE: Peace Lily Question

I think it's more of a nuisance than a disaster. Spathiphyllums are pretty easy like that.


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RE: Peace Lily Question

Are you talking about breaking the leaf blade from the petiole? See the diagram here for definitions of the parts I'm referring to. I'm being specific about terminology for the sake of clarity--the "stems" that the leaves attach to are actually just another part of the leaves (the petiole).

As a rule, new leaves only emerge from the plant's meristem (the growing bit at the tip of the stem--which is of course hidden from view in aroids like PL), and that entails the petiole+blade as a single unit, as implied above. The meristem is essentially the factory for creating leaves (and inflorescences and any other new growth) in the plant's shoot, and it can only do it at the tip.

So while the plant can grow new leaves and pop them out from its center, it doesn't have the ability to regrow existing ones in the same place as they were if they've been cut off--whether you cut the leaf in half or cut/break it off right up to the petiole, it doesn't make a difference.

I hope that gives a little background as to why leaves can't be exactly replaced. :)

Diagram I linked comes from this page, which is also an interesting and detailed read in its own right:
More Spath Info (source page of diagram).


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RE: Peace Lily Question

Toni and tropicbreezent: thanks for the information!

hexalm: Sorry for my lack of better terminology. Yes, I broke the leaf blade off from the petiole and just the petiole is left. My concern was that if this was the newest petiole created, will me having broken it off, keep the peace lily from producing more petioles/leaf blades? I am suspecting no as the meristem sounds to be a completely different "thing" in a completely different area than the petiole that broke, but I just wanted to clarify my question better. Thanks again.

Planto


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RE: Peace Lily Question

I tend to gloss over terminology often enough myself, but was just being extra specific to make sure I understood the question :)

You're correct though, the meristem moves on to its next project once it creates a leaf, so damage to existing leaves shouldn't be an issue and you'll almost certainly see another new leaf soon (in fact, leaf damage like that tends to stimulate new growth).


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RE: Peace Lily Question

Planto, hexalm's right. New leaves will grow.

Hex, out of curiosity, why and how does leaf damage stimulate new growth?

I've read damaged/marred leaves should be removed, otherwise nutrients focus on the ruined leaf..


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RE: Peace Lily Question

It depends on the type of damage, but in general I think it's a response to herbivores. (Though herbivores browsing on a plant can cause a host of different reactions, including production of compounds to cope better with damage or to discourage herbivores from eating.)

I'm not sure about the exact mechanism, but all I'm really saying is that if you tear a leaf off, the plant needs to replace the leaf. Same concept as pruning.

I think you're right that if the leaf has damage and is still attached (or if its removal caused major damage elsewhere), that can sap resources--if nothing else, just by using nutrients from the roots that could instead be invested in new, nicer leaves.


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RE: Peace Lily Question

That's right, if a leaf has its area reduced then it can't take up the same amount of resources from the roots. This then gets channeled to the 'next project', ie a new leaf. If it's only partly damaged then it might still be able to draw off most of the resources thus preventing rapid growth of a new leaf. It's all a matter of degrees.


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RE: Peace Lily Question

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Sat, Jun 23, 12 at 7:02

Chemical messengers give plants a 'sense' of whether parts like leaves and branches are net users or net producers of energy than we have, so while it's fine to remove a few damaged leaves from healthy plants, some consideration should be given to how much photosynthesizing machinery we remove from plants that are struggling. If a plant is clinging desperately to 12 leaves and 6 of them aren't pretty, it's probably better to live with the unsightly foliage than to remove somewhere around half of the plant's ability to make food.

When a leaf becomes a net user of energy, the plant sheds it, and often but not always grows a new leaf from latent buds in the leaf axil (crotch), which is why it's important to cut through the petiole (leaf stem) at some point or through the leaf itself, as close to the stem as possible to avoid damaging a latent bud when removing leaves. Avoid pulling or tearing them off. The plant will soon shed what's remaining of the leaf.

In bonsai, we often cut leaves in half on vigorous branches or toward the top of apically dominant plants to force energy allocation to weaker plant parts. You may have noted a few conversations that included tips on energy management that included removing leaves or cutting back strong areas of plants to force back-budding or more growth in areas that are weaker energy sinks, which is all part of the same theme. I notice that when I'm cutting leaves by a fraction, if I go too far and cut too much of the leaf off, the plant will shed the leaf and grow another.

Leaves shed due to a lack of auxin flow from the leaf. Auxin is produced primarily in apical meristems, but in leaves, too. A continual polar flow (shoots to roots) of auxin across the abscission zone at the base of leaves or petioles is required to keep an abscission layer from forming. Once the leaf is damaged to the degree it is not producing enough auxin to prevent the abscission layer from forming, the layer forms and the leaf is shed. At the same time, the reduction in auxin flow allows another growth regulator to become dominant. The growth regulator, cytokinin, is produced in roots and moves from roots to shoots, opposite the polar flow of auxin. Cytokinin stimulates lateral breaks; that is, it stimulates latent buds into activity. So, as the leaf is being shed due to a lack of auxin, the surge in cytokinin is stimulating a new bud to take the old leaf's place. In some plants, apical dominance is so strong and the flow of auxin so great that this doesn't occur at all.

Al


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RE: Peace Lily Question

Thanks for the detail, Al! I figured it was about auxin ;)


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RE: Peace Lily Question

hexalm,
Thanks so much for the information!

Planto


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RE: Peace Lily Question

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Sat, Jun 23, 12 at 21:22

The opening sentence was missing a word. It was supposed to read Chemical messengers give plants a better 'sense' of whether parts like leaves and branches are net users or net producers of energy than we have, ....

Sorry it didn't make sense. Still, I hope you found value in the offering.

Al


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