Now You See Em . . . Now You Don't! - Orchid Board

lornaheath · #1 07-23-2013, 08:38 AM

Hello Orchid World Friends,

Can anyone explain please about Roots!

When I look, I often find that a root started out well and nice, then there's a section of dead root, then it has another section of 'came back to life root' on the end?

How the gubbins does that happen if the middle section died?? Dur!

I sometimes try to pull off a dead bit of root sticking above the mix, only to find that it has 'Alive' bits on both ends of the dead bit?

Me totally baffled with this one.

Lorna
x x x

tucker85 · #2 07-23-2013, 09:12 AM

I've experienced that also. The root is actually a very thin and very tough material that looks like a thin piece of wire in the center of the root structure. The outer coating of the root is a sponge-like material call velamen. Apparently the velamen can become degraded die off while the tiny root inside is still alive. That's why you occasionally get a new root growing from the end of a root that looks dead. What causes the velamen to be destroyed is another matter that I haven't completely figured out. Lack of moisture or low humidity may have something to do with it or maybe harsh chemicals and strong fertilizers degrade it, I really don't know. Never-the-less it does happen.

RosieC · #3 07-23-2013, 09:28 AM

Yeah, happens to me too. My understanding is the same as Tucker's.

Discus · #4 07-23-2013, 09:48 AM

If you'll forgive the biology/anatomy: Strictly speaking, the "velamen" is only that outer whitish layer. The stringy, wiry bit seems to be called a "stele"; the bit between those two is "cortex". IIRC, this "wiry" bit is the vascularised tissue (i.e. the bit that carries water etc), which would then make this effect plausibly viable for the plant. I have not seen this in my plants, but I've certainly seen plenty of bare stele!

p104 of http://www.analelesnbc.ro/arhivapdfvol16issue2/12.pdf has some nice, labelled cross sections and additional details, although the english is marginal.

lornaheath · #5 07-23-2013, 09:54 AM

O M G Discus that is immense. Thank you so much for making time to share that info. I really appreciate it and I'm sure dozens of others will too.

BIG Hugs for you Young Man.

Lorna
x x x

Discus · #6 07-23-2013, 09:56 AM

Looking at living things at the microscopic level is fascinating.

I had the opportunity to work with a Scanning Electron Microscope in my Honours research project. They are fun, fun toys.

RosieC · #7 07-24-2013, 03:15 AM

I've heard it said that the bit at the end after the bare area won't live long. I'm not sure if this is the case, I've certainly seen growth below it, but how long that has lasted compared to 'healthy' roots I don't know.

The other thing I've found is that after a massive amount of root rot plants have done better (mostly oncidium types in my case) if I left on the Stele than if I cut them off. One part of that might be stability in the pot, but I've had the impression (and it may be no more than an impression) that these plants have also been able to stay better hydrated.