Change in root color

[King_of_orchid_growing:)]

Phal roots should be green if they've been exposed to light, or turn green when the silvery white velamen gets wet if the cortex tissue was green to begin with, no matter what species or hybrid they are.

I have not had the experience of roots exposed to light not being green for a Phal. They pretty much are green when they are exposed to light. I can provide many photos of my own plants of this.

The light levels they are exposed to will usually determine the pigmentation of the root tips. Some Phals are more predisposed to genetically have root tips that are reddish-brown than others and if the environment is conducive in allowing the reddish-brown pigmentation to present itself in the plant, it will.

The only exceptions would be if the Phal's root tips are genetically predisposed to have a different color or if the root had not been exposed to light.

Roots that have too little exposure to light or no light exposure may not have chlorophyll in visually detectable amounts, and therefore, not show up as being green. No chlorophyll or no visibly detectable amounts of chlorophyll will also mean no green roots/root tips. They will in essence be mostly translucent white with a yellowish tip.

Chlorophyll is the green pigmentation. Yellow/yellowish tint is one of the carotenoid pigments, which would be exposed to some degree if the Phal's roots had no chlorophyll.




I thought we were strictly talking about root tip pigmentation in the original post. Not the color of the entire root.

So, again, as far as i know, the current understanding is…

A Phal's root is structured like so, (please click on link):

Aerial root of orchid

The above link shows a thin cross section of an orchid's roots under a microscope. Do not pay attention to the colors of the cells that the slide presents. Those colors are not necessarily representative of what the orchid root's natural cell pigmentation are. The cells were dyed with certain chemicals to make the tissue layers on the slide more visible to the viewer. I provided the link as more of a demonstration of how each general layer of tissues in the orchid's roots are organized.

The outermost layers of tissues of the root would be known by most as the velamen.

There is a fleshy middle layer of tissues that is generally called the cortex.

The center/core is generally where the vascular bundle/vascular tissues would be. (It's that stringy portion of the root.)

The cortical layer, (aka the middle layer), is where the pigments would be.

Q: Why is it that the middle layer of tissues, (aka the cortex), is the one that contains the pigmentation?

A: Because the velamen layer consists mostly of dead cells. Also because certain portions of the vascular bundle consists mostly of non-living cells.

The cells in the cortex are the ones that are alive.

It is very evident that in the cortical layer of a Phal's root there are two general types of pigments:

a) chlorophyll pigments (shades of green)

b) carotenoid pigments (shades of red, yellow, and orange)

It is important to note that cortical type cells that are completely devoid of pigmentation is translucent.

Chlorophyll pigments are present when there is a light source.

Chlorophyll help the chloroplasts make sugars for the plant's cells by utilizing light.

Lack of light exposure will not favor chlorophyll to be present in large amounts. So if you see roots that are translucent white and have a yellowish tint, certain cortical cells may have no pigmentation whatsoever, have very visually undetectable amounts of chlorophyll pigments, or have visually detectable amounts of carotenoid pigments but these cells may be scattered sparsely throughout the roots.


Now, plants in general have a third known type of pigment called anthocyanins, that are responsible for violets and purples. This pigmentation will surface if:

A) The plant is predisposed to genetically be able to produce the pigment when needed.

B) Is exposed to a significant amount of light without burning the plant's cells.

C) Will be present in certain parts of the plant regardless of the level of light exposure.



While it is not 100% clear to me as to what makes the reddish brown coloration of the root tips, I do know that a plant, (in this case, we're talking about a Phal specifically), carries these 3 general types of pigments, (anthocyanin, chlorophyll, carotenoid). As a result, I believe that a reddish-brown coloration could be the result of a combination of carotenoids, chlorophyll, and anthocyanin pigments presenting itself together, (provided we are talking about living, healthy cells and not those that are bruised or sunburnt).

[james mickelso]

Some of my phals have root tips that are and remain brownish or reddish. Others have clear root tips and others which have greenish root tips. Regardless of light levels. All receive the same amount of light. It's interesting that cattleya and laelias never, at least in any of mine, have green roots. They are exposed to light levels much higher than phals and still have white roots. As they age and the velamen becomes more open and spongy they turn a silver gray color when wet but never green. I would assume that the velamen is the same structurally and chemically in both plants. I wonder why this is different.

[katrina]

Originally Posted by james mickelso

It's interesting that cattleya and laelias never, at least in any of mine, have green roots.

Some of my catt roots turn green when well watered. I don't recall how many or what percentage but I know some do.

[Brooke]

Originally Posted by King_of_orchid_growing:)

Phal roots should be green if they've been exposed to light, or turn green when the silvery white velamen gets wet if the cortex tissue was green to begin with, no matter what species or hybrid they are.

I have not had the experience of roots exposed to light not being green for a Phal. They pretty much are green when they are exposed to light. I can provide many photos of my own plants of this.

The light levels they are exposed to will usually determine the pigmentation of the root tips. Some Phals are more predisposed to genetically have root tips that are reddish-brown than others and if the environment is conducive in allowing the reddish-brown pigmentation to present itself in the plant, it will.

The only exceptions would be if the Phal's root tips are genetically predisposed to have a different color or if the root had not been exposed to light.

Roots that have too little exposure to light or no light exposure may not have chlorophyll in visually detectable amounts, and therefore, not show up as being green. No chlorophyll or no visibly detectable amounts of chlorophyll will also mean no green roots/root tips. They will in essence be mostly translucent white with a yellowish tip.

Chlorophyll is the green pigmentation. Yellow/yellowish tint is one of the carotenoid pigments, which would be exposed to some degree if the Phal's roots had no chlorophyll.




I thought we were strictly talking about root tip pigmentation in the original post. Not the color of the entire root.

So, again, as far as i know, the current understanding is…

A Phal's root is structured like so, (please click on link):

Aerial root of orchid

The above link shows a thin cross section of an orchid's roots under a microscope. Do not pay attention to the colors of the cells that the slide presents. Those colors are not necessarily representative of what the orchid root's natural cell pigmentation are. The cells were dyed with certain chemicals to make the tissue layers on the slide more visible to the viewer. I provided the link as more of a demonstration of how each general layer of tissues in the orchid's roots are organized.

The outermost layers of tissues of the root would be known by most as the velamen.

There is a fleshy middle layer of tissues that is generally called the cortex.

The center/core is generally where the vascular bundle/vascular tissues would be. (It's that stringy portion of the root.)

The cortical layer, (aka the middle layer), is where the pigments would be.

Q: Why is it that the middle layer of tissues, (aka the cortex), is the one that contains the pigmentation?

A: Because the velamen layer consists mostly of dead cells. Also because certain portions of the vascular bundle consists mostly of non-living cells.

The cells in the cortex are the ones that are alive.

It is very evident that in the cortical layer of a Phal's root there are two general types of pigments:

a) chlorophyll pigments (shades of green)

b) carotenoid pigments (shades of red, yellow, and orange)

It is important to note that cortical type cells that are completely devoid of pigmentation is translucent.

Chlorophyll pigments are present when there is a light source.

Chlorophyll help the chloroplasts make sugars for the plant's cells by utilizing light.

Lack of light exposure will not favor chlorophyll to be present in large amounts. So if you see roots that are translucent white and have a yellowish tint, certain cortical cells may have no pigmentation whatsoever, have very visually undetectable amounts of chlorophyll pigments, or have visually detectable amounts of carotenoid pigments but these cells may be scattered sparsely throughout the roots.


Now, plants in general have a third known type of pigment called anthocyanins, that are responsible for violets and purples. This pigmentation will surface if:

A) The plant is predisposed to genetically be able to produce the pigment when needed.

B) Is exposed to a significant amount of light without burning the plant's cells.

C) Will be present in certain parts of the plant regardless of the level of light exposure.



While it is not 100% clear to me as to what makes the reddish brown coloration of the root tips, I do know that a plant, (in this case, we're talking about a Phal specifically), carries these 3 general types of pigments, (anthocyanin, chlorophyll, carotenoid). As a result, I believe that a reddish-brown coloration could be the result of a combination of carotenoids, chlorophyll, and anthocyanin pigments presenting itself together, (provided we are talking about living, healthy cells and not those that are bruised or sunburnt).

Nice essay King but I stand by my original short post of some Phal growing root tips are green and some growing root tips are brown/reddish in color.

To add additional information about Phal root tips, some quit growing, usually in winter, the velamin covers over the tips and you won't see a colored tip.

I grow 50/60 Phal species mounted so I can observe their habits year round. I have a schilleriana and a sanderiana growing right next to a gigantea. The schillie and sanderiana have brown-ish tips and the gig has green root tips and they get the same exposure to sun.

I also grow many Phals in air cone pots so they have some exposure to light - some are green and some are brown/red-ish in color. Again same light exposure.

When the green root tipped Phals are watered, their roots turn green. When the other type are watered, the roots darken in color but will. never. turn. green.

Brooke

[King_of_orchid_growing:)]

What about comparing Phal schilleriana to a few Phal schilleriana, instead of Phal schilleriana to Phal gigantea?

A small group of Phal schilleriana in one location with one light source all getting similar strength of light exposure.

Then compare to another group of Phal schilleriana in another location with another light source getting a radically different strength of light exposure to the 1st group.

When done gathering the info for the second group, change the light exposure again to a different strength.

What would the results be?


Then, what would the result be for comparing Phal sanderiana to Phal sanderiana?

Have these been taken into account?

I'm curious to know.


I'm not discounting that you are an experienced and accomplished grower of Phals. I acknowledge that you have been able to successfully grow Phals for quite a while.

But, if what you claim is true, then I'd like to know whether it really is true or not, because that's not what I see. Maybe there's something I haven't seen before. If so, I want to know.

So the question still stands…

What about comparisons between Phal schilleriana to Phal schilleriana; or comparisons between Phal sanderiana to Phal sanderiana? At this point I'm more interested in this answer rather than a cross comparison between 2 different species of Phals.



Another question would be - what about comparing different individual strands of root from one individual Phal that has the brown root tip trait? If one root on one individual Phal was exposed to light, and another root on the same individual Phal was not, would the 2 roots be the same pigmentation?

[lotis146]

I just received a Phal Brother Lawrence x Yellow Brite Lites as a gift with a purchase and its leaves in addition to its roots are a darker color with some reddish/brown hues. The roots velamen is more greyish and the tips are brownish. I wonder if this is what Brooke is referring to.

I don't know the conditions this plant was under before it arrived here and I've had it almost a week.

[Brooke]

Originally Posted by King_of_orchid_growing:)

What about comparing Phal schilleriana to a few Phal schilleriana, instead of Phal schilleriana to Phal gigantea?

A small group of Phal schilleriana in one location with one light source all getting similar strength of light exposure.

Then compare to another group of Phal schilleriana in another location with another light source getting a radically different strength of light exposure to the 1st group.

When done gathering the info for the second group, change the light exposure again to a different strength.

What would the results be?


Then, what would the result be for comparing Phal sanderiana to Phal sanderiana?

Have these been taken into account?

I'm curious to know.


I'm not discounting that you are an experienced and accomplished grower of Phals. I acknowledge that you have been able to successfully grow Phals for quite a while.

But, if what you claim is true, then I'd like to know whether it really is true or not, because that's not what I see. Maybe there's something I haven't seen before. If so, I want to know.

So the question still stands…

What about comparisons between Phal schilleriana to Phal schilleriana; or comparisons between Phal sanderiana to Phal sanderiana? At this point I'm more interested in this answer rather than a cross comparison between 2 different species of Phals.



Another question would be - what about comparing different individual strands of root from one individual Phal that has the brown root tip trait? If one root on one individual Phal was exposed to light, and another root on the same individual Phal was not, would the 2 roots be the same pigmentation?

no thanks I don't perform experiments, I just grow orchids. I'm sure if you do the experimenting people will be interested. Take lots of pics and share them on the forum.

Yes Lotis the Phal you just received has the roots I am describing.

Brooke

[yousillygirl]

Originally Posted by King_of_orchid_growing:)

Another question would be - what about comparing different individual strands of root from one individual Phal that has the brown root tip trait? If one root on one individual Phal was exposed to light, and another root on the same individual Phal was not, would the 2 roots be the same pigmentation?

Ha, by pure dumb luck, I know the answer to this question.

I have a phal that simultaneously put out about 5 roots all the way around the plant (*thank you, seaweed!). The roots on the sun-facing side of the plants are all bright green, with the slightly reddish tip. The roots on the other side of the plant, which emerged lower on the plant stem and burrowed under the hydroton quite quickly, are that pale light yellowy-green color and the tip is a slightly darker yellow-green, but no redness.

[King_of_orchid_growing:)]

Originally Posted by yousillygirl

Ha, by pure dumb luck, I know the answer to this question.

I have a phal that simultaneously put out about 5 roots all the way around the plant (*thank you, seaweed!). The roots on the sun-facing side of the plants are all bright green, with the slightly reddish tip. The roots on the other side of the plant, which emerged lower on the plant stem and burrowed under the hydroton quite quickly, are that pale light yellowy-green color and the tip is a slightly darker yellow-green, but no redness.

Thank you.