I mentioned Cattleya schilleriana recently in my post about spotted Cattleyas. It is one of my most favorite of all orchid species. I have been trying to grow it better then I have in the past.
This past Sunday, Alan Koch revealed the true secret of schilleriana culture. His lecture was on specific cultural techniques for orchid species. He mentioned that they have recently discovered that Cattleya schilleriana lacks stomata in its leaves. Stomata allow for the exchange of gasses from the plant with its environment. BUT wait, where are the stomata?? Doesn't every plant have them? Yes they do. Cattleya schillerianas stomata are in the roots!! Oh my.
Now he didn't say specifically who "they" were but this explains a lot. Alan claimed since the roots need to breathe, you should not pot them at all.
I admit, this gorgeous species has puzzled me for years,


I have sent many of them to Orchid Heaven! Limited successes encouraged me to keep trying. Plastic pots, clay pots, mounted, none offered long term success. Perhaps the stomata hold the key.
The three I have now I have had since Florida. Which for me might be a record for longevity. They are growing in heavy duty, smallish black plastic open baskets. The media is loose charcoal, aliflor and sponge rock. They are growing well but have not bloomed. But that is likely a light issue.
But the whole moral to the story is to attend as many lectures as you can. Read as many articles as you can because you never quite know where important tid- bits of information might be obtained. This past Ann Arbor meeting was one such event! I am so glad I went. Now all I need are flowers!!

Curiosity question...If the stomata are in the roots, why use any medium at all? Why not just drop them bare-root into a basket? Or hang them from a wire?

Like a Turtle that.... https://funfactz.com/animal-fa...

Thanks for sharing this important info Bill!

That is of course true. Media is completely not needed.
But a lot of orchid growers grow their plants in some type of container, be it a clay or plastic pot or maybe a basket. Some growers, with species in particular, experience a whole host of issues regarding the culture of species. They can be very cantankerous!
Hybrids though are generally thought to be easier due to something called hybrid vigor. This is often the case with primary hybrids, a species X with a species. The hybrid grows better because it can grow well in a broader range of conditions. The conditions preferred by both parents can be tolerated by the offspring.
But in dealing with species and species culture, certain growers like the challenge afforded by growing species. Plus me personally take a great deal of pride in growing something a bit more difficult and getting it to flower.

But in all of my experience, to find out that stomata on the roots may hold the key is what is amazing. I just wonder how and why they stumbled upon this possible solution.
Sometimes you just have to be a crazed Orchid Nut like me to understand. It's just that since the 1850's, people have tried to match a particular orchid with a specific media. It just was a bit of a shock to learn about the stomata.

I used to grow my Cattleya schilleriana for years bare root in a large Bonsai dish, in full sun and with mostly daily watering. It did really well like that for quite some years.
Schomburgkia superbiens grows best simply dumped bare root into a large clay pot and let it take off from there. And many others....

Now regarding the stomata on on those roots - well yes! I am a bit confused, isn't that the function of the velamen which covers the roots of epiphytic Orchids, that its stomata help in preventing water loss and aid in absorption of water and nutrients. I am only surprised that schilleriana leaves don't have stomata, hmmm. There is no question regarding the root structure.
How is the gas exchange during photosynthesis accomplished in those schilleriana leaves without stomata? The leaves are green!!

Evidently there are stomata only in the roots! What I wanted to know is:who thought to check that??
Must have been a frustrated schilleriana grower like me!
Stomata are cells that function like 'trap doors'. They are usually located on the underside of the leaves from what I understand. That is why foliage feeding of orchids is not very useful. The gray stuff that turns green when watered is velamin. I never heard of it having much to do with air or gas transfer. And I also gather that they are not normally found on roots. The green of a leaf is from chlorophyll, photosynthesis and food production.
Another BIG point that Alan was trying to make was that with several orchids, he has turned to translucent pots. Apparently research indicates that with some orchids, there is much more in the way of root photosynthesis then previously thought.

I just read the notes from lectures Alan Koch has given all the way back to 2015 saying Cattleya schilleriana is the only Cattleya with stomata on its roots so must be mounted, or grown with roots exposed or in course medium.

(This is apparently something the Orchid Guys have known for awhile and forgot to share. ) His comments leave me confused because none of the notes clarify. Did he mean this is the only Cattleya with stomata on the roots, but not the leaves? Or the only Cattleya with stomata on the roots in addition to the usual ones on the leaves?

Now I have to go write Alan an email...

I don't know if it is the only Cattleya with stomata on its roots, but it is unusual. And he did specifically say that there were none on the leaves of that species.
He did say to grow it mounted and that pots or containers with media would not work.
Mine are in those wide banded, kind of heavy duty little black slotted baskets, similar to a plastic net pot. I have very little media in the basket because the slots are so wide that media falls out easily leaving the roots well exposed compared to a pot.
Normally I would consider changing to a mount like he suggests except bifoliate Cattleyas hate to be disturbed!! Mine seem fine in that I have not killed them like so many others. If I buy another, and knowing my lust for this species, I probably will, that one will be mounted.

Daisy, I am truly looking forwards to his answer.
I figured maybe schilleriana is one of those thick leaved plants/Cacti which go through CAM cycle by closing their pores during the hot days to preserve moisture. I always thought that the thick velamen on Orchid roots also has pores/stomata, facilitating nutrients and water exchange. Isn't that one of the characteristics of epiphytic Orchids?
I am certainly confused here too....

Okay, here is Alan's answer:

Yes, C. schilleriana has stomata in the leaves like all orchids with the vast majority on the underside of the leaves. I have never said it does not have stomata elsewhere.
alan

Ursula, there is at least one video floating around out there showing a drop of water sitting on an orchid root. And then you just see the velamin kind of move a little just a bone dry sponge would move as it absorbs water. And as it moves, it goes from light gray to green/gray to green as the water is absorbed.
I thought that the velamin is a layer, or layers, of specialized cells that have some type of " bonding agent" which allows the root to adhere to the host that enables the root/plant to stick to the host.
I don't think that I have ever heard of stomata in roots before. I just thought it was leaves and in reference to orchids, on the undersides of the leaves mostly.

But his talk wasn't on stomata it was on little nuances that have been found and these nuances having been found were making it easier to grow certain orchids.

Okay. Now with Alan's answer I am lost! He made a point about not putting them in pots. Stomata on the roots.
I am going back to my original growing method. Buy them and slowly kill them no matter what I do.
At least in my world, that's normal.

I hear you Bill!
It sounds like I assigned the specific term of stomata in velamen "somewhat too happily".
Now I need to get another C. schilleriana!

BigBill said:Okay. Now with Alan's answer I am lost! He made a point about not putting them in pots. Stomata on the roots.
I am going back to my original growing method. Buy them and slowly kill them no matter what I do.
At least in my world, that's normal.

Or you could put one in a basket without any potting medium and see if it dies more slowly.