Just exactly what color is the cambium anyway?

[Olpea]

I know this seems like a simple question, but I don’t think it is. One poster touched on this very briefly in another thread, but I thought I’d start a thread to ask this question more formally.

I’ve always read/heard the cambium is the green tissue under the bark. The problem I have with this is that when T-budding the rootstock, I’ve not noticed any green tissue touching the newly placed bud. In other words, when opening the “T” I see blond “naked” wood on the little trunk, and blond colored wood on the inside of the bark. The "green tissue is on the bark, but it’s not exposed when opening the little bark flap. It’s behind the blond colored bark. So when the new bud is placed inside the “T” on the rootstock, no green tissue from the rootstock touches the little new bud chip.

Furthermore, for improved success rates, it’s recommended to remove the little piece of wood in the bud chip, so that the bud chip doesn’t have any wood to interfere with the contact of the bud chip and the cambium (I sometimes do this if the little piece of wood is easy to remove.) My question is, how can the cambium be green, when all I see is blond wood on the trunk where the bud chip slips in.

I think this is an especially relevant question given that we can’t seem to figure out the color of a white and gold internet dress

Seriously though, it does not seem to make sense that the cambium is green.

Appleseed posted this video some time ago. In it the grafter says the cambium is a “dark translucent line” (he doesn’t say green). Then if you watch carefully, he follows the cambium with his knife and his knife blade runs just underneath the green bark (I’ve watched it several times. At the top of the cut in the scion, the green tissue is several millimeters thick, and he runs the point of his knife blade underneath that, to show where the cambium is.) Here is the video. The part I’m referring to starts at about 9 minutes in the video.

https://www.youtube.com/watch?v=f4ReeuSPGh4

I once asked someone who runs a small nursery this same question years ago, and he told me the cambium is green, but he couldn’t address these surrounding questions. I’m wondering if he just didn’t give me a “stock” answer. Any thoughts?

[tonyOmahaz5]

Here is a photo of different layers inside the trunk. Hope that will help.

Tony

[alan]

That proves it. That cambium is really green

But how come it doesn’t look like the photo of the cut on the cherry tree?

[Matt_in_Maryland]

Olpea,

I have wondered the same thing when T-budding. I lay the shield inside the bark flap upon the tannish white part labeled “outer rings” in the picture above. I imagine the cambium is indeed the green part, but as the juices are flowing, callous tissue begins to build all around & glops up the whole area inside, essentially grabbing the bud-shield & locking it into place.

-Matt

[warmwxrules]

green stuff

[Olpea]

Well, unless anyone can come up with something better, I think Matt hast he best explanation. That is, T buds really don’t connect to the cambium.

This has important ramifications for the often repeated “truism” that cambiums much touch. Far from it, cambiums can seem to be completely separated by some other layer (which is a different color) and still connect with callus tissue.

In my mind, this reinforces my experience that temps are more critical than cambium match and precise cuts.

[AJfromElmiraNY]

Interesting topic. I know the cortex layer initially has chloroplasts that produce chlorophyll for photosynthesis. As the cork layer gets thicker it blocks light to chloroplasts and eventually they stop producing chlorophyll. In the picture of the bud shield above you can see the very dark green layer just inside the outer brown cork layer. To my knowledge, the vascular tissue in woody plants do not have chloroplasts that produce chlorophyll. That makes me wonder if the lighter green in the center of the bud shield is just from light conductance by the translucent vascular cells.

[Olpea]

OK,

I’ve done a bit more reading, and as far as I can tell, what people are calling the “green” cambium is really the phloem. The vascular cambium (where cell division occurs-the equivalent of stem cells in people) is what you want to line up. The vascular cambium is underneath and much thinner than the green phloem.

If the green phloem is lined up, then it seems to me it’s almost certain the cambium will also be lined up.

That said, I still haven’t found any definitive color pictures of the various layers of bark for “young” tree bark (i.e. the age typically grafted) which would positively identify the color of the cambium.

However, based on the video above, the individual said the cambium was a “dark translucent line”. This makes sense with the pic Warmwx posted. Notice the very fine brown line below the green layer in the bud chip in the pic. I think that is the cambium.

Whether you agree or not, thanks Frank for posting such a good pic.

[Matt_in_Maryland]

Olpea et al,

Below are photos of me T-budding an apple this past August. Picture #1 clearly shows the tannish white layer behind the flaps where I placed the bud-shield. Picture #4 was taken a few weeks later and shows the rootstock’s progress in absorbing the bud. Callous tissue formed-- adhering to the bud-- eventually swallowing it up.

When the rootstock bark is “slipping” in August (peels back easily because it is still actively growing), the green layer of cells is actually part of what peels back. See pics below.

Kevin Hauser of Kuffell Creek Apple Nursery has posted a video on T-budding that can easily be found on YouTube which similarly describes the process (that’s where I got the idea!). Cheers,

-Matt

[Olpea]

You’re right Matt. Even if the cambium is right next to the green phloem, the cambium on the chip bud is still in no way contacting the cambium on any part of the rootstock. I think the blond colored bark on the inner surface of the bud flap is the xylum. In other words, from outside to inside, I think the green is the phloem, next is the very thin line of the vascular cambium, followed by the blond colored xylum. If this is the case, the only part of the flap in the rootstock which comes into contact with the bud chip is the xylum.

It must be as you say, the “juices” inside the “T” cut on the rootstock apparently feed the bud chip enough to cause replication of the cambium cells, forming callus tissue and eventually “welding” the chip in place until eventually the callus tissue connects the cambium of the rootstock with the cambium of the bud chip.

[tonyOmahaz5]

Matt & Olpea,

I agreed with you guys about sap “juices”. I also do an additional step by cutting a small angle cut on the bottom back side of the bud to expose more of the cambium layer. I have very good success with T-budding. In addition, when I do bark grafting with that bottom back side angle cut plus two small side cuts of the scion for more cambium exposure. I learned this trick from Joe Real tutorial. Lucky P. pointed out to me.

Tony

[fruitnut]

The cambium is a very thin layer only a couple cells thick. It’s not the green in post 5 of warmwxrules. It’s between the green and the wood inside that. The open T flap in post 9 shows cambium on the wood side and it’s off white or blond.

If you take the wood out of the bud there is full contact of the two layers of cambium.

Then you open the T or remove the wood from bud you are ripping the cambium layer in half. Some stays on wood and some on bark.

Bark is slipping when cambium is actively laying down new wood inside and new bark outside. Pulling the bark off wood rips cambium in two very thin layers still attached to each side.

[Olpea]

Fruitnut, If the blond wood in the bud flap picture is the cambium, where is the xylem?

Below is a link which shows the anatomy of bark. By clicking on various parts, it highlights different parts of the picture.

http://www.ujaen.es/investiga/atlas/atlas_ingles/tallohibiscus/tallohibiscus10xcortex.htm

I’m not necessarily disagreeing, just trying to sort this out in my own mind.

[fruitnut]

Xylem is the wood right? It’s just inside the cambium. The cambium forms wood on it’s inner surface and bark on it’s outer. The cambium is about the thickness of a piece of paper.

When you strip bark off rapidly growing wood, there is a small layer of cambium inside the bark and outside the wood.

[Chills]

I’m very interested in this discussion because while I have propagated by many means, I have not yet had any success grafting. What is the easiest species or plant to try on for beginners to be successful?

Thank you

Chills

[fruitnut]

Try apples or pears first.

[Olpea]

According to the following link, Fruitnut seems to be correct. The link has a pretty good diagram (third illustration down).

http://pharamcytimes.com/tag/plants-conducting-elements/

In that sense xylem is just the wood. This surprised me because I knew xlyem transported water/nutrients from roots to foliage, but I thought this occurred only on the outside bark. This makes sense to me (in one sense) because I’ve seen trees completely hollowed out by rot, but still alive, with just a really thick layer of bark. However, in that case, there must be just enough xylem tissue in the thick bark to transport water/nutrients back up the tree.

A few years ago I completely girdled a couple elm trees (to kill them) but I was surprised they made it through two summers before they died. Upon reflection, this would seem to confirm the xylem is in the wood itself, else how would the tree remain alive for two summers?

Referring back to the illustration I linked above and applying it to Matt’s pic of the open bud flaps, the vascular cambium is indeed what Fruitnut refers to. It’s more or less invisible (or indistinguishable) from the xylem (blond wood on the little trunk) and the blond colored phloem on the inside of the bark flaps. It would make sense it’s “invisible” if it’s only a couple cells thick, as fruitnut suggests.

So the order from outside to inside seems to be: cork bark (we all know that is brown), cork cambium (maybe that’s the green stuff, but that’s not the type of cambium which concerns grafters), blond colored phloem (fairly thick layer), invisible vascular cambium (for grafters, this is where the “pay dirt” is, even though the pay dirt is extremely thin), the xylem (which is basically the wood-the “sap wood” in illustration Tony provided). Lastly is the heart wood (which is the very core of the tree and probably it’s only function is structural strength).

Thanks for all the responses. If I have this right, I’ve definitely learned something. Either way, the cambium which concerns grafters is not green, nor is it a dark line (but it can be just “inside” the green on brand new shoots, i.e. current season growth). I bet I’ve read a hundred times the cambium is green (and repeated it some myself) which is incorrect. I find that somewhat amazing. That is, that the general consensus of even trusted publications can be incorrect on something which should be a fairly straightforward anatomy question.

[fruitnut]

All one needs to know to graft or bud is where the cambium is located. That’s the part that separates when the bark peels off wood.

One other thing I’d point out in post 9 above of Matt’s second picture down. The cambium would be only in a very thin strip around the small elliptical area of whitish wood in the center of that bud. All the light green material outside the elliptical area of wood is probably bark. The bark won’t heal to wood of stock. Graft will likely succeed esp on apple but is cut a little too thin to include much cambium layer, IMO.

[marknmt]

Well, this is a very useful thread. I’ve always wondered about this issue and now I think we have the answer.

But it does make me wonder just how thick (not very!) those two cells of cambium make the layer which has now been identified as a grafter’s pay dirt. Would you have to use a microscope to see the individual cells, or would a good jeweler’s loupe do it? I imagine somebody knows how to stain the cells to make them stand out better. That would be interesting, and might even be useful in practice.

[fruitnut]

You won’t see them with any kind of hand lens.

The cambium layer changes very rapidly. Cut off the water and those cells quit dividing. Then the bark won’t slip and you can’t T bud. Water heavily and in 7-10 days the cambium is dividing rapidly, bark slips, and T budding is on.