I was re-reading previous posts on Renanthera and the discussion
wandered into watering aerial roots. Several people mentioned roots
turning green.
I have noticed that some of my plant's roots turn green instantly and
others take a much longer time. Some do not turn green at all.
Neostylis, Christieara and Phalaenopsis are in the former group. As
soon as water hits them the roots begin to darken. Dendrobium
biggibum, Sophronitis cernua and Laeliocattleya Little Stars only get
some green patches ( at best), even after fifteen or twenty minutes in
a bucket of water. They all look fine, making new growth and
flowering regularly.
I'm wondering if because of the low relative humidity in my
conditions, the velamen on certain plants becomes less permeable,
protecting against water loss? With the consequence of making it
harder to absorb water?
Neostylis, Lc and the Phals are potted in bark, while Den. and Soph.
are on bark mounts with a wee bit of sphagnum moss. The Christieare
is in a basket with several large chunks of bark.
I'm wondering if those of you with greenhouses also observe this
phenomenom?
What about Those of you who grow outside all year? ( I'm not angry
because you can - I'm angry because I can't! --- LOL)
Thanks for letting me share!
Bob Campoli - Philadelphia, Pa - growing plants on a windowsill.

I am struggling to recall which study showed that velamen is totally impermeable and that only the green root tips can absorb water. From that, you can take it that relative humidity doesn't have a part to play here. The trick here is to get your aerial roots to attach to something. It is at this junction that water is taken up.

But if the velamen is impermeable, why then do roots go green when I water them?

Weng

An interesting question, Bob.

I see something similar, and I grow in a greenhouse, so the humidity is
usually quite good. I have always chalked it up to individuals, rather than
type of plant, but maybe I just didn't catch the connection.

The velamen is supposed to capture water, and I had never heard of the
"prevent moisture loss" concept applied to it.

Might it have something to do with age, or maybe what the conditions were
like when the roots grew? The concept there is that maybe - if the plant
was watered well during the time of the growth of those specific roots - the
velamen was not a crucial part of the uptake mechanism, so didn't develop to
absorb as readily as that that grew under drier conditions.
--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies. Books, Artwork, and lots of Free Info!


"bobc" wrote in message
ups.com...
I was re-reading previous posts on Renanthera and the discussion
wandered into watering aerial roots. Several people mentioned roots
turning green.
I have noticed that some of my plant's roots turn green instantly and
others take a much longer time. Some do not turn green at all.
Neostylis, Christieara and Phalaenopsis are in the former group. As
soon as water hits them the roots begin to darken. Dendrobium
biggibum, Sophronitis cernua and Laeliocattleya Little Stars only get
some green patches ( at best), even after fifteen or twenty minutes in
a bucket of water. They all look fine, making new growth and
flowering regularly.
I'm wondering if because of the low relative humidity in my
conditions, the velamen on certain plants becomes less permeable,
protecting against water loss? With the consequence of making it
harder to absorb water?
Neostylis, Lc and the Phals are potted in bark, while Den. and Soph.
are on bark mounts with a wee bit of sphagnum moss. The Christieare
is in a basket with several large chunks of bark.
I'm wondering if those of you with greenhouses also observe this
phenomenom?
What about Those of you who grow outside all year? ( I'm not angry
because you can - I'm angry because I can't! --- LOL)
Thanks for letting me share!
Bob Campoli - Philadelphia, Pa - growing plants on a windowsill.

I always found that a few of my Aussie native dens have a very interesting
velamen in that they turn splotchy when wet. They appear as mostly white,
but have a few green spots.

Kye.

"Ray B" wrote in message
news:0XQ9i.13456$Gy4.3106@trndny08...
An interesting question, Bob.

I see something similar, and I grow in a greenhouse, so the humidity is
usually quite good. I have always chalked it up to individuals, rather
than type of plant, but maybe I just didn't catch the connection.

The velamen is supposed to capture water, and I had never heard of the
"prevent moisture loss" concept applied to it.

Might it have something to do with age, or maybe what the conditions were
like when the roots grew? The concept there is that maybe - if the plant
was watered well during the time of the growth of those specific roots -
the velamen was not a crucial part of the uptake mechanism, so didn't
develop to absorb as readily as that that grew under drier conditions.
--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies. Books, Artwork, and lots of Free Info!


"bobc" wrote in message
ups.com...
I was re-reading previous posts on Renanthera and the discussion
wandered into watering aerial roots. Several people mentioned roots
turning green.
I have noticed that some of my plant's roots turn green instantly and
others take a much longer time. Some do not turn green at all.
Neostylis, Christieara and Phalaenopsis are in the former group. As
soon as water hits them the roots begin to darken. Dendrobium
biggibum, Sophronitis cernua and Laeliocattleya Little Stars only get
some green patches ( at best), even after fifteen or twenty minutes in
a bucket of water. They all look fine, making new growth and
flowering regularly.
I'm wondering if because of the low relative humidity in my
conditions, the velamen on certain plants becomes less permeable,
protecting against water loss? With the consequence of making it
harder to absorb water?
Neostylis, Lc and the Phals are potted in bark, while Den. and Soph.
are on bark mounts with a wee bit of sphagnum moss. The Christieare
is in a basket with several large chunks of bark.
I'm wondering if those of you with greenhouses also observe this
phenomenom?
What about Those of you who grow outside all year? ( I'm not angry
because you can - I'm angry because I can't! --- LOL)
Thanks for letting me share!
Bob Campoli - Philadelphia, Pa - growing plants on a windowsill.

Good topic for discussion. I find that among groups of our plants the degree
of "greenness" varies. Some of the Phals, notably the ones with thinner
roots, green up immediately. But we have some that have much thicker roots,
and in order to get them green it takes a good deal more water. I have made
the assumption (yes, I know, that's dangerous) that the dark green roots
cannot absorb much more. So far, the growth rates in both types are similar.

Bob, with regard to your biggibum, the roots on our superbums green only at
the tips. The same goes for reed stem Epis. And the variation in "greening"
in our Vandaceous plants is enormous.

We grow outside under screen.

Diana

"Kye" wrote in message
...
I always found that a few of my Aussie native dens have a very interesting
velamen in that they turn splotchy when wet. They appear as mostly white,
but have a few green spots.

Kye.

"Ray B" wrote in message
news:0XQ9i.13456$Gy4.3106@trndny08...
An interesting question, Bob.

I see something similar, and I grow in a greenhouse, so the humidity is
usually quite good. I have always chalked it up to individuals, rather
than type of plant, but maybe I just didn't catch the connection.

The velamen is supposed to capture water, and I had never heard of the
"prevent moisture loss" concept applied to it.

Might it have something to do with age, or maybe what the conditions were
like when the roots grew? The concept there is that maybe - if the plant
was watered well during the time of the growth of those specific roots -
the velamen was not a crucial part of the uptake mechanism, so didn't
develop to absorb as readily as that that grew under drier conditions.
--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies. Books, Artwork, and lots of Free Info!


"bobc" wrote in message
ups.com...
I was re-reading previous posts on Renanthera and the discussion
wandered into watering aerial roots. Several people mentioned roots
turning green.
I have noticed that some of my plant's roots turn green instantly and
others take a much longer time. Some do not turn green at all.
Neostylis, Christieara and Phalaenopsis are in the former group. As
soon as water hits them the roots begin to darken. Dendrobium
biggibum, Sophronitis cernua and Laeliocattleya Little Stars only get
some green patches ( at best), even after fifteen or twenty minutes in
a bucket of water. They all look fine, making new growth and
flowering regularly.
I'm wondering if because of the low relative humidity in my
conditions, the velamen on certain plants becomes less permeable,
protecting against water loss? With the consequence of making it
harder to absorb water?
Neostylis, Lc and the Phals are potted in bark, while Den. and Soph.
are on bark mounts with a wee bit of sphagnum moss. The Christieare
is in a basket with several large chunks of bark.
I'm wondering if those of you with greenhouses also observe this
phenomenom?
What about Those of you who grow outside all year? ( I'm not angry
because you can - I'm angry because I can't! --- LOL)
Thanks for letting me share!
Bob Campoli - Philadelphia, Pa - growing plants on a windowsill.

On Jun 7, 6:17 am, "Ray B" wrote:
An interesting question, Bob.

I see something similar, and I grow in a greenhouse, so the humidity is
usually quite good. I have always chalked it up to individuals, rather than
type of plant, but maybe I just didn't catch the connection.

The velamen is supposed to capture water, and I had never heard of the
"prevent moisture loss" concept applied to it.

Might it have something to do with age, or maybe what the conditions were
like when the roots grew? The concept there is that maybe - if the plant
was watered well during the time of the growth of those specific roots - the
velamen was not a crucial part of the uptake mechanism, so didn't develop to
absorb as readily as that that grew under drier conditions.
--

Ray Barkalow - First Rays Orchids -www.firstrays.com
Plants, Supplies. Books, Artwork, and lots of Free Info!

Hi Ray!
I don't know if it's due to age or not. I've always noticed the way
my plants roots responded to the application of water, but never
questioned it before. I'm going to try and pay closer attention for
the next few weeks to see how the various roots on each plant
responds.
I did notice last night, watering the Den biggibum, that the oldest
part of the root darkened rather quickly. And the closer to the
growing tip, the whiter the velamen. I'm going to see if that holds
true for the other plants as well.
Another interesting thing I noticed is the growing tip of the root on
the Christieara is reddish ... I believe most, if not all the other
plant's root tips are green.
Bob

Some orchids definitely have different root colors. My Max. schunkeana has
dark purple roots with little light green tips, and I've seen Bulb.
purpureorachis with lighter reddish-purple roots and long green tips. The
roots can be pretty cool looking.
-danny

On Jun 7, 4:31 pm, "Diana Kulaga"
wrote:
Good topic for discussion. I find that among groups of our plants the degree
of "greenness" varies. Some of the Phals, notably the ones with thinner
roots, green up immediately. But we have some that have much thicker roots,
and in order to get them green it takes a good deal more water. I have made
the assumption (yes, I know, that's dangerous) that the dark green roots
cannot absorb much more. So far, the growth rates in both types are similar.

Bob, with regard to your biggibum, the roots on our superbums green only at
the tips. The same goes for reed stem Epis. And the variation in "greening"
in our Vandaceous plants is enormous.

We grow outside under screen.

Diana
Hi Diana,
So apparently this greening isn't due to the low relative humidity in
my house. You're in Florida, I believe and Ray has a greenhouse, and
you both have noticed the same thing. As does Kye.
My general assumption was that velamen, functioning to absorb water,
would be very quick to grab it as available. And the green color was
due to the chlorophyll in the roots becoming visible. I guessed my
relatively dry atmosphere caused the velamen to thicken (maybe), and
the root would become green quickly to maximize water intake. Even
perhaps going so far as to perhaps develop a one way mechanism - quick
on the uptake, slow to evaporate. As opposed to a high RH situation
where the velamen didn't have to work so hard. There being plenty of
moisture in the air. ( I kind of expected that in a high RH situation
orchid roots would be green most or all of the time. There would be
no real change of color).
When I started to pay attention, however, I didn't see the quick
greening of roots like I expected. At least not on every exposed
root. Encyclia tampensis is another one in that the greening is so
faint that unless I look closely, it appears white. And that has lots
of exposed roots. The bigibbum that I thought stayed white really has
some very faint green after watering.
Well got to go ... my daughter needs the computer for school.
Have a great day!
Bob Campoli

Someone in our local society mentioned that the water temperature can have a
big effect on how quickly the roots turn green. He said warmer water turns
them green faster.
-danny

I just returned from a business trip, so sorry if this is late, but I have a
vanda in the GH that is totally unpotted, hanging from a wire.

The roots that grew last year sort of stopped over the winter. This spring
they all stated to branch like crazy. The "old part" greens up rapidly when
sprayed, the new growth does not.

From that, what do we speculate?

--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies. Books, Artwork, and lots of Free Info!


"danny" wrote in message
...
Someone in our local society mentioned that the water temperature can have
a big effect on how quickly the roots turn green. He said warmer water
turns them green faster.
-danny

Ray

I have noticed the same thing with my Vandas. If you rub the old part when
wet it seems to green up quicker. Is there a protective coating on the
older part of the root?
John



"Ray B" wrote in message
news:nZXbi.7251$c45.4905@trndny06...
I just returned from a business trip, so sorry if this is late, but I have
a vanda in the GH that is totally unpotted, hanging from a wire.

The roots that grew last year sort of stopped over the winter. This
spring they all stated to branch like crazy. The "old part" greens up
rapidly when sprayed, the new growth does not.

From that, what do we speculate?

--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies. Books, Artwork, and lots of Free Info!


"danny" wrote in message
...
Someone in our local society mentioned that the water temperature can
have a big effect on how quickly the roots turn green. He said warmer
water turns them green faster.
-danny

On Jun 13, 5:52 pm, "John Varigos"
wrote:
Ray

I have noticed the same thing with my Vandas. If you rub the old part when
wet it seems to green up quicker. Is there a protective coating on the
older part of the root?
John

"Ray B" wrote in message

news:nZXbi.7251$c45.4905@trndny06...



I just returned from a business trip, so sorry if this is late, but I have
a vanda in the GH that is totally unpotted, hanging from a wire.

The roots that grew last year sort of stopped over the winter. This
spring they all stated to branch like crazy. The "old part" greens up
rapidly when sprayed, the new growth does not.

From that, what do we speculate?

--

Ray Barkalow - First Rays Orchids -www.firstrays.com
Plants, Supplies. Books, Artwork, and lots of Free Info!

"danny" wrote in message
. ..
Someone in our local society mentioned that the water temperature can
have a big effect on how quickly the roots turn green. He said warmer
water turns them green faster.
-danny- Hide quoted text -

- Show quoted text -

Speculate? Ok now my head is starting to hurt! LOL
Thinking does that to me sometimes G

However, it leads me to think the older roots or older parts of a root
are quicker to grab water. There must be something on or in the newer
velamen resistant to water uptake ... some kind of waxy coating?
Perhaps to facilitate sliding through .... wait, there is no
substrate.
Maybe to protect the newest parts of the root from drying out as they
grow? Doesn't water and nutrients flow throughout a plant?
Regardless of which part of the plant absorbs it? Roots are important
to a plant and extra protection to the more fragile ( or delicate?)
tips while they are developing seems reasonable. Perhaps once the new
root stops growing, rests, then begins growing again ... that part of
the root loses the waxy coating ( or whatever it might be) and now
absorbs water quickly.
Gotta go ... daughter's done work and I gotta pick her up.
Have a great day!
Bob Campoli