Healthy roots at the end of "rotting" ones

[MateoinLosAngeles]

It's been a long time since I stopped trimming any roots when repotting my orchids. If I do, it's usually for space reasons or if the velamen is completely absent. Even then, sometimes I leave them. If I perceive a noticeable rot odor, then I cut them, but being mushy is not usually enough of a reason for me.

Many AOS webinars and youtube videos mention that mushy roots are dead and that the stele can't uptake any water or nutrition on its own. Yet, in many instances, I see very healthy roots growing at the end of mushy roots or even bare stele.

I recently saw an AOS webinar that suggested these roots were dead on arrival since they couldn't transport anything to the plant due to the middle stele being dead tissue. Yet there must've been some information transport through this "dead tissue" for the ends to grow healthy velamen. When a lizard losses its tail, a new lizard doesn't grow from the severed limb, yet a new tail grows from the living lizard.

I'm bringing this up in hopes of finding more information on whether "dead" roots are actually "dead" or if this myth of cutting mushy roots is one to be busted.

[orchidman77]

Following as I've noticed the same thing in plenty of my plants!

David

[Ray]

(Uh-oh! A thought provoking subject while drinking my first cup of coffee. Danger, danger!)

I think there may be two scenarios that may look similar to the casual observer that are really entirely different.

The root tip is the apical meristem of that structure. Once it is dead, the growth will not proceed further. It may, however, form lateral apices and branch.

The other case involves a break in the outer layers that exposes the stele, and the outer tissues near the break decompose a bit, exposing more of the stele, leaving viable zones of functioning roots on either side.

I’m guessing that the cells of the stele are nourished primarily by surrounding tissue, but may be thin-walled enough that the chemicals they deliver may diffuse into them, as well.

I suspect that - like apparently everything else- it’s a matter of degree. A short gap exposing the stele having a longer period of viability that does a long stretch of exposed “string”.

[DirtyCoconuts]

here's my take. who cares? and i am not being glib, but leave the roots. Unless it is hurting the plant (like rotting and creating a septic area in the growing area) leave it. if the roots are just surviving and not helping the plant, so what? if they are working and helping, albeit at a reduced rate, great. i feel that roots have multiple purposes and the anchor/ guy wire use is certainly still helpful even if completely dead. i keep the roots intact and use them to help stabilize the plant and perhaps they are also helping the nute uptake.

i have certainly seen healthy growing tips on the ends of roots i thought were dead to the core

[Roberta]

Another reason for leaving roots even if they just have the core, is that when you repot, stability of the plant is vital for new roots to grow. If the plant wobbles, those new growing root tips get damaged and they stop growing. A bad root may still have the ability to hydrate the plant, but in addition it's a "handle" to hole the plant in place while it grows new ones.