Orchids roots growing away from light?

[rbarata]

It happens with most of the orchids I have with aerial roots (catt, onc).
What's the reason?

Thank you

[Subrosa]

Just a guess, but if they grew out into the sun they'd dry out faster.

[katrina]

Originally Posted by Subrosa

Just a guess, but if they grew out into the sun they'd dry out faster.

That and the "dark" side of a plant is usually the side where the tree is and they are seeking an attachment site. The tendency is even more noticeable in my hoyas.

[Ray]

Originally Posted by katrina

That and the "dark" side of a plant is usually the side where the tree is and they are seeking an attachment site. The tendency is even more noticeable in my hoyas.

Yep! And the shade would be where there is a greater likelihood of holding moisture.

[rbarata]

I see, but this does not happen with phals, for ex.
Phal roots can make photosynthesis so they search for light.
Is is true to say that the "away from light" behaviour is more pronounced in "non-photosynthetic" roots?

[Lady Oscar]

Originally Posted by rbarata

I see, but this does not happen with phals, for ex.
Phal roots can make photosynthesis so they search for light.
Is is true to say that the "away from light" behaviour is more pronounced in "non-photosynthetic" roots?

I'm definitely seeing the aerial roots of my phal that lives next to a window growing straight back away from the window. However, I think this location gets a little too much light for it, so maybe that's why?

[rbarata]

I'm definitely seeing the aerial roots of my phal that lives next to a window growing straight back away from the window. However, I think this location gets a little too much light for it, so maybe that's why?

Mine grow in every direction but there's a tendency for them to start first in locations faced to the window, directly to the light source.

[estación seca]

My Vandas in glass vases frequently grow roots straight up, as though trying to escape the vase. I wonder whether they're growing towards less heat or away from more humidity.

[katrina]

Originally Posted by rbarata

I see, but this does not happen with phals, for ex.
Phal roots can make photosynthesis so they search for light.
Is is true to say that the "away from light" behaviour is more pronounced in "non-photosynthetic" roots?

Roots in orchids do several things but w/out finding a source to attach themselves to they wouldn't be secure so I think their first priority would be attachment, second would be photosynthesis. It's pure conjecture, but I don't believe they are seeking light like leaves need light so I think it's just one of those crazy things that orchids tend to do. No real rhyme or reason for it...it just happens.

FWIW - I have phal roots that do the same...grow away from the light. But, I also have some that grow everywhere. And, I have catts with roots that grow in all directions.

[Orchid Whisperer]

In general, my orchids also seem to grow in directions that will give them a better "hold" in the growing medium or on a mount, or they grow to accumulate more growing medium (e.g., for me, some "trash basket" Oncidiums; also seen with Ansellia and Gramatophyllum). They never seem to be putting much effort into seeking out the light.

Although I don't discount that orchid roots do photosynthesize, I think that for most leafy orchids, anchoring the plant and capturing water and nutrients are the main root functions.