Rooting cuttings with no nodes?

[TooCoys]

I've started this thread twice already and deleted what I had typed because I'm having a hard time wrapping my head around it.

I understand that rooting plants with nodes is probably easier because of the barrier at the node - it's like a wall where all the hormones collect causing root growth.

However, once a plant/tree gets woody like say a crepe myrtle, do the nodes disappear? Is that why the air layering technique works? Because you're basically creating a "node" or a spot for rooting hormones to collect?

And this is where I really get confused - my young JM's have clearly defined nodes which I assume would make them just as easy to root as a young crepe myrtle shoot. However, my two young Chinese Elm's do not have nodes on the "trunks". Would the first node be where the branches are coming out on those?

It's 4:30am, I should probably quit watching youtube already.

 

[TooCoys]

...and if you can root a branch from just under a node, or where a secondary branch comes out, can you go out and cut say a 2" branch off a crepe myrtle and root it, and make a new tree out of it?

 

[Wires_Guy_wires]

The barrier is just not where the hormones collect, it's also a place where cells actively divide, it's also a place that plants can close off when there's an infection.

Branches can come from nodes, but also from bare trunks in most species. If that's the case, they can also produce roots from those locations.

Air layering is the process of conversion. Cells transform from regular tissue to root tissue, sometimes some kind of stem cells are actively transported to that location.

You can always make trees from branches.

Hope this helps.

 

[0soyoung]

The process of generating adventitious roots has no direct connection to nodes. That is, adventitious roots can be generated anywhere along the length of a stem. It is all about a local auxin excess. On the other hand, buds are auxin sources and occur only at nodes. Hence a cutting must have a bud (that is at a node).

It continues to dazzle me that new shoots can only come from a node (a point where, once upon a time the was a leaf and an axillary/fascicular bud), but roots can be made anywhere! I still don't understand why that is, even if I'm wrong about the extent of this generality. It must lie in (what I presume to be fact that) cytokinins cannot cause de-differentiation of cambium cells - is there a connection to PAT (polar auxin transport)?

Is my thinking different from yours @Wires_Guy_wires, or are we on the same page?
This is very interesting stuff, IMHO.

 

[sparklemotion]

The process of generating adventitious roots has no direct connection to nodes. That is, adventitious roots can be generated anywhere along the length of a stem. It is all about a local auxin excess. On the other hand, buds are auxin sources and occur only at nodes. Hence a cutting must have a bud (that is at a node).

It continues to dazzle me that new shoots can only come from a node (a point where, once upon a time the was a leaf and an axillary/fascicular bud), but roots can be made anywhere! I still don't understand why that is, even if I'm wrong about the extent of this generality. It must lie in (what I presume to be fact that) cytokinins cannot cause de-differentiation of cambium cells - is there a connection to PAT (polar auxin transport)?

Is my thinking different from yours @Wires_Guy_wires, or are we on the same page?
This is very interesting stuff, IMHO.

Adventitious buds are also a thing -- many many trees will sprout shoots from non-nodes. (wikipedia link, but I'm pretty sure that Castaño discusses this in Botany for Bonsai). Consider how branches sprout after trunk chops (on amenable species)...

You might be thinking of the phenomenon of "blind" leaf cuttings, that will root, but never form buds. I'm pretty sure there are a limited number of species that will do that. (link to discussion of hoya and ficus elastica), and it's from lack of any stem tissue at all, not from lack of nodes.

 

[sparklemotion]

And to answer (one of) the original question(s):

...and if you can root a branch from just under a node, or where a secondary branch comes out, can you go out and cut say a 2" branch off a crepe myrtle and root it, and make a new tree out of it?

It appears that photobucket has tried to eat @bonhe's picture from this thread:
https://www.bonsainut.com/threads/cutting-back-crepe-myrtles.15385/

It came up on google image search so I hope no one minds me reattaching it here...

In the picture are 4 large cuttings I made more than one month ago. Each cutting is about 10 cm diameter. The new shoots are coming from every where now

 

[0soyoung]

Adventitious buds are also a thing -- many many trees will sprout shoots from non-nodes. (wikipedialink, but I'm pretty sure that Castaño discusses this in Botany for Bonsai). Consider how branches sprout after trunk chops (on amenable species)...

You might be thinking of the phenomenon of "blind" leaf cuttings, that will root, but never form buds. I'm pretty sure there are a limited number of species that will do that. (link to discussion of hoya and ficus elastica), and it's from lack of any stem tissue at all, not from lack of nodes.

More specifically, I'm basically thinking in terms of maples with distinct nodes. Ring the stem, add a moist environment and I get roots at the ring, not at the node above. It doesn't matter where this ring is in relation to the node, roots can develop there. Buds only appear at, and pop from, the node(s) below. They never, for instance emerge from the ring of cambium at the bottom of the girdle, nor anywhere in between there and the node below. I've played variants of this game with zelkova and seijus elms, horsechestnuts and it seems that buds/shoots only appear from nodes, IMHO.

Rhododendrons/azaleas have 'eyes' along stems that are dormant buds. I think these were at the base of a scale when the shoot first formed - sort of an axillary bud analogous to scale buds on pine candles. I think of these in the same way even though it may not properly be defined as a node. The point is that buds don't occur just anywhere - they appear at specific locations. One can apply cytokinins to release them but cytokinins won't induce a bud at any arbitrary location in the fashion that an excess of auxin will induce the formation of root initials, anywhere.

... that's my thinking, that's my fog of confusion.

Thanks for your citations and time.

 

[sparklemotion]

Some of this may be getting muddled by not talking about specific-species. But Acers (maples) will form adventitious buds, but are more likely to rely on a previously formed dormant bud. (preventitious vs. adventitious budding, in this paper).

But even those dormant buds don't aren't necessarily formed at "nodes."

As for why dormant buds pop before adventitious buds form? Don't quote me on this, but I'm pretty sure it's because the dormant buds are already there, lying in wait, when something happens to the auxin flow that was suppressing them. It makes a lot more sense for the tree to open up buds that already existed than to make whole new ones.

Adventitious roots are probably more common because (evolutionarily speaking) in the wild, there isn't much call to grow whole new roots (as opposed to the need for trees to replace a branch/leader). So there aren't a whole bunch of root meristems lying in wait underneath the bark of most species.

 

[0soyoung]

Okay, good paper (based on a quick skim).

So, I have a terminology problem: I talk in terms of acer palmatums, despite playing with lots and lots of azelea/rhododendrons and pines. Well despite playing with over 50 different species. I guess what I should have been saying is something to the effect that buds occur only at locations that were defined when the stem first grew. I don't believe it is possible to induce a bud just anywhere on an existing stem analogously to growing roots at any point of my choosing.

Anyway, I've got to carefully read this paper.
Thanks, @sparklemotion !

 

[TooCoys]

So, I have a terminology problem: I talk in terms of acer palmatums, despite playing with lots and lots of azelea/rhododendrons and pines.

@sparklemotion !

I was speaking in terms of crepe myrtles.

We have this large one right next to our RV. It has lots and lots of trunks. Most are smooth up until the shoots and are all 2-3” in diameter.

How would you root that without an air layer if you just went out and chopped one down?

 

[0soyoung]

I was speaking in terms of crepe myrtles. We have this large one right next to our RV. It has lots and lots of trunks. Most are smooth up until the shoots and are all 2-3” in diameter.

How would you root that without an air layer if you just went out and chopped one down?

If it was chopped down, there are only possibilities. One is to wait for the roots to make new shoots, whether you leave the stump in the ground or dig it and pot it. The other is to cut a short length of stem with a leaf, treat the root-ward end of that stem with rooting hormone (to boot up the rooting process), strike it in a rooting medium (bonsai substrate, peat plug, perlite, etc.), put it into a terrarium, and out of direct sunlight, then wait. It is a race against time - grow roots before the cutting desiccates. It does matter where you cut the stem relative to a node, If you get roots for form, they will be at, or very close to, the cut surface.

If the tree remains as is, one can air layer a stem. The standard way of doing this is cut a ring of bark away from the stem. Just as with a cutting, it does not matter where you do this along the length of the stem, if roots form. the will be at the top of the ring of missing bark, in the analogous position of a cutting. The advantage of layering is that the xylem (wood) remains in tact and there is no race against time because the wood of the mother plant is intact and continues to supply water to the 'clone'.

The only relevance of a node in all of this is with regard to the aesthetics of your newly rooted plant. If you want a branch close to the soil level, then you would have cut the stem, or girdled the stem, at that distance below the branch/node. If there are no branches and no discernible nodes/buds then it is catches catch can where they might subsequently appear.

 

[Wires_Guy_wires]

The process of generating adventitious roots has no direct connection to nodes. That is, adventitious roots can be generated anywhere along the length of a stem. It is all about a local auxin excess. On the other hand, buds are auxin sources and occur only at nodes. Hence a cutting must have a bud (that is at a node).

It continues to dazzle me that new shoots can only come from a node (a point where, once upon a time the was a leaf and an axillary/fascicular bud), but roots can be made anywhere! I still don't understand why that is, even if I'm wrong about the extent of this generality. It must lie in (what I presume to be fact that) cytokinins cannot cause de-differentiation of cambium cells - is there a connection to PAT (polar auxin transport)?

Is my thinking different from yours @Wires_Guy_wires, or are we on the same page?
This is very interesting stuff, IMHO.

Our thinking is more or less the same, but I think our experiences differ. As long as there are cells that can still differentiate, they can in fact form buds. It doesn't really matter where on the plant they are.
I used to think in frames like "one node = one set of buds" but after seeing plants produce them from callus, from roots, from leaf tissue, and from internodal wood, I can't be sure anymore. Now I adjusted the frame to "if pluripotent cells available, then bud/shoot formation is possible".
It differs a lot if, and where they're available and the responsivenes of the plant is always an issue. Some plants need dormant 'eyes' to keep those cells at locations, others can just transport them to where they're needed and some others can redifferentiate on the fly.
Roots are easier to form, I believe, because the genes needed to become roots are closer to cambium or other vascular tissue compared to leafs, buds and meristems. The redifferentiation steps are fewer, and they are smaller. But if you have 2 years time, you could theoretically, produce adventitious shoots anywhere.

 

[0soyoung]

But if you have 2 years time, you could theoretically, produce adventitious shoots anywhere.

I've got 2 years. I've wasted more than that naively trying to do it with living trees (woody plants, anyway) and gotten nowhere other than more puzzled.

 

[jmw_bonsai]

To go along with this discussion, what is everybody's thoughts on ideal place to cut for Acer palmatum cuttings? I usually cut just below a node, so there isn't much space between the cut and the node/buds. I also rub off the buds, especially if they are a larger bud type. So I would think my roots are forming on the stem above the node. Would it be better to cut in between nodes and use the lower stem below the node for rooting. I just assume the node had a good cutoff for health. Often ill notice the stem lower than the node dies off/turns black up until the node.

 

[TN_Jim]

I was speaking in terms of crepe myrtles.

We have this large one right next to our RV. It has lots and lots of trunks.

Most are smooth up until the shoots and are all 2-3” in diameter.

How would you root that without an air layer if you just went out and chopped one down?

This thread is going deep, good things.

Regarding your question:

About a month ago I got two crepes, chopped a large leading branch from both (~1”). Both were about 1’ long.

On a whim I whittled down two sides with pocket knife into about a 4” V (maintaining intact bark on either side of the taper) -looked ideal for dispatching a vampire.

I stuck both into a 8” pot with regular old potting soil left over from some herbaceous plant that didn’t make it. Also, I reduced leaves on both to 3. No rooting hormones applied.

I placed this pot in shade under tree bench and watered it every time I watered my trees.

Long story short, one died & the other started throwing abundant buds/leaves, doing well, just gave to a friend.

Also, @Osoyoung, your peroxide leaf treatment has been an absolute game changer. I can not speak highly enough regarding this technique. Great thanks and praise to you my friend.

I actually would not have got these two trees had I not seen this approach change/heal my trees -they were both ridiculous with leaf spot when I got them, all gone now, trees look great..and sending new branches everywhere.

Thanks