What is CAM?
Under natural conditions, the acid content of certain succulent plants increases at night and decreases the following day. This type of diurnal variation in acidity was first discovered in Crassula sp., hence the name. Crassulacean Acid Metabolism is abbreviated as CAM. This important strategy that enables thick-leaved orchids to minimize water loss is shared with cacti, bromeliads and euphorbias. Having CAM permits orchids to control water loss by restricting exchange of carbon dioxide, oxygen and water vapor to evening hours.
Orchids that do not use CAM open their pores during the day andclose these at night. Pores are open during daylight hours when photosynthesis can happen. Water vapor, carbon dioxide and oxygen move through the pores. Non-CAM orchids include most Paphiopedilums. Many thin-leaved orchids have non-CAM leaves and CAM positive pseudobulbs.
Orchids using CAM close their pores during the day and open the pores at night. Of course, the plants must photosynthesize during the day when the pores are closed. To accomplish this, carbon dioxide is absorbed at night then fixed as malic acid. The acid is stored as liquid in sacs (vacuoles) within special cells in the leaf, stem or pseudobulb. The next day, the acid is metabolized so that photosynthesis can take place.
Preliminary evidence suggests that certain orchids may enter dormancy in response to water stress or drought. During forced or natural dormancy, the plant will be in an ‘idling phase'. During the ‘idling phase', stomata remain closed day and night. Carbon dioxide and water are recycled with minimal acidity flux. During this drastic form of water conservation, a plant will not grow but it will survive much longer than if it did not have CAM.
One way to detect CAM is to take small sections of leaf, crush in a equal quantity of deionized water then measure the acidity (pH). This can be done at home with a relatively inexpensive pH meter. Plants practicing CAM will show an increasing acidity (decreasing pH) as the evening progresses. Once morning comes, acidity will diminish and the pH will rise. Known CAM plants that are in the ‘idling phase' will show an uncharacteristic lack of fluctuation.
If you ever wondered why an orchid just wouldn't start growing, maybe it is simply a matter of having the correct temperature and moisture/humidity both day and night to release a CAM plant from self-imposed dormancy or ‘idling phase'.
Pre-discussion Material, Wed 14 May 97
WONDERING WHY
by Marilyn H. S. Light
Part 1. It's just a matter of degree.
Have you ever wondered why an orchid just won't grow? Maybe it is simply a lack of nutrients or light or water but often it is a matter of having the correct temperature both day and night to release a plant from self-imposed dormancy. It never ceases to amaze me how having the correct temperature regime does wonders for an orchid. Sometimes the temperature being provided is too low: a few degrees can make a warm-growing Vanda sulk. Even Brassavola nodosa will refuse to grow roots if kept too cool. Inappropriate day and night temperatures make susceptible orchids batten down the hatches and wait for better weather. Watering and misting will be mostly in vain: the sulking plant will simply not absorb water. It may take some time before the orchid to die but die it will if conditions are not changed for the better. It is easy to say "change the temperature" but which way is the way to go? Cultural hints such as warm, intermediate and cool are only guidelines. It takes the curious orchidist to find out what makes a particular orchid behave the way it does, and then try something new to make the orchid thrive.
I grow a wide variety of species and hybrids. My favorites are those that thrive despite me and the growing environment I can provide. For those few that like the temperature just so, I have developed a way to discover their exact needs.
Several minimum/maximum digital recording thermometers are needed to monitor the growing area. Such devices are relatively inexpensive ($20) and the recording feature means that you do not need to get up in the wee hours before dawn to verify the night minimum. A notebook is essential to keep track of data, changes and results.
First monitor the existing conditions that an orchid does not seem to like them move the orchid to a warmer or cooler spot. For example, if the existing temperatures are approximately 60°F night/66°F day, and if the orchid is an intermediate to warm grower according to cultural guides, try placing the plant in a warmer place. The temperature should be 5 to 10°F warmer, especially during the day. Monitor the orchid daily. Mist regularly but do not apply fertilizer. (For really dehydrated plants, place them in a poly bag with a few strands of damp sphagnum moss) If the temperature change is beneficial, a plant will almost always perk up. While new roots may not begin to appear for several weeks, the plant will begin absorbing water through existing live roots. A plant can change for the better in as little as 48 hours!
If there is no effect of the temperature change and perhaps more importantly, if the plant appears to suffer from the change, reassess the situation. Remove the plant back to the original condition or to the opposite (cooler or warmer) regime.
Raising seasonally dormant orchids requires an understanding of how they enter and exit the dormant period. Often, as in the case of Pleione, a particular temperature treatment at the appropriate stage in a plant's life (chilling fully mature plants to near 32°F in late September), will enable the plants to become completely dormant. Keeping them through winter then requires only cool, dry storage for four or five months. Each species and hybrid will exit dormancy according to its particular ‘clock' and the grower will have to respond accordingly.
It is easy to oversimplify cultural technique. There are no simple answers to what are complex problems. Orchids that fail to thrive could be suffering from viral disease or any number of cultural challenges other than temperature regime. Inappropriate temperature is, however, an important factor that should not be overlooked.
Part II. The Succulent Lifestyle
Orchid plants have several strategies that enable them to conserve water. Among these are Reflective leaf surface as in Stelis gemma; Waxy, water repellent cuticle as in Zygopetalum sp.; Specialized water storage cells as in Paphiopedilum concolor; Closeable pores (stomata) as in Cattleya sp.; Reduced leaf surface area (terete leaves or no leaves at all as in Angraecum subulatum; and Specialized metabolism (Crassulacean Acid Metabolism) as in Doritis pulcherrima.
Crassulacean Acid Metabolism (CAM)
Under natural conditions, the acid content of certain succulent plants increases at night and decreases the following day. This type of diurnal variation in acidity was first discovered in Crassula sp., hence the name. Crassulacean Acid Metabolism is abbreviated as CAM. This important strategy that enables thick-leaved orchids to minimize water loss is shared with cacti, bromeliads and euphorbias. Having CAM permits orchids to control water loss by restricting exchange of carbon dioxide, oxygen and water vapor to evening hours.
Orchids that do not use CAM open their pores during the day and close these at night. Pores are open during daylight hours when photosynthesis can happen. Water vapor, carbon dioxide and oxygen move through the pores. Non-CAM orchids include most Paphiopedilums. Many thin-leaved orchids have non-CAM leaves and CAM positive pseudobulbs.
Orchids using CAM close their pores during the day and open the pores at night. Of course, the plants must photosynthesize during the day when the pores are closed. To accomplish this, carbon dioxide is absorbed at night then fixed as malic acid. The acid is stored as liquid in sacs (vacuoles) within special cells in the leaf, stem or pseudobulb. The next day, the acid is metabolized so that photosynthesis can take place.
Preliminary evidence suggests that certain orchids may enter dormancy in response to water stress or drought. During forced or natural dormancy, the plant will be in an ‘idling phase'. During the ‘idling phase', stomata remain closed day and night. Carbon dioxide and water are recycled with minimal acidity flux. During this drastic form of water conservation, a plant will not grow but it will survive much longer than if it did not have CAM.
One way to detect CAM is to take small sections of leaf, crush in a equal quantity of deionized water then measure the acidity (pH). This can be done at home with a relatively inexpensive pH meter. Plants practicing CAM will show an increasing acidity (decreasing pH) as the evening progresses. Once morning comes, acidity will diminish and the pH will rise. Known CAM plants that are in the ‘idling phase' will show an uncharacteristic lack of fluctuation.
If you ever wondered why an orchid just wouldn't start growing, maybe it is simply a matter of having the correct temperature and moisture/humidity both day and night to release a CAM plant from self-imposed dormancy or ‘idling phase'.
Chat Synopsis: 14 May 97
In this presentation, Marilyn categorized cultural requirements by CAM:
1) Raising non-CAM plants like Masdevallia, Disa and Paphiopedilum;
2) Growing seasonally deciduous orchids like Pleione or Lycaste;
or 3) Growing CAM orchids such as Cattleya, Phalaenopsis.
marilyn001)
I understand that Lois sent out some notes and a graph. Has anyone any questions they would like to raise tonight?
I think we will stay here if that is alright with everyone. I will go over to ICS and post a note there.
marylois)
Oh, dear! What a night to be delayed! Glad you are just starting, Marilyn - but know the preceding transcript will be interesting! Hi, all y'all! (that's plural!)!
Any newbie here who wants a copy of Marilyn's pre-discussion paper - email me marylois@prysm.net
Fleur)
Marilyn, I noted that you grow Masd, how do you treat them?
marilyn001)
I grow a variety of Masdevallias and have recently ventured into raising warm-growing ones. Most of the Masdevallias I grow are intermediate growers. While the leaves of Masdevallias are succulent, they do drink a lot of water. I grow them in living spahgnum moss at 15-18C.
Fleur
Very much the way I grow mine then, in live sphagnum moss and cool.
Carol Holdren
I grow my Masd. in fine tree fern.
marilyn001
I thought you might like to discuss growing any of the three major types of orchids.
1) Raising non-CAM plants like Masdevallia, Disa and Paphiopedilum;
2) Growing seasonally deciduous orchids like Pleione or Lycaste;
or 3) Growing CAM orchids such as Cattleya, Phalaenopsis.
Andy NVA
My vote is to discuss home growing of disa. Is it possible? If so.... How?
Fleur
I grow members of the first two groups but not the last, catts just up and die on me.
bmtorchids(Barbara in Sunny California)
My Disa is in bud, they do take a long time. The last one it bloom for me for so long, and I over water it, it went..... that way.
marilyn001
I have noted that some Masdevallias must be grown cool/cold in winter to bloom well in mid summer when it is hot. Masd. peristeria is one such character.
Gaillevy
I'd love to be able to grow disas, HOW!!!
bmtorchids(Barbara in Sunny California)
Yes Andy, we all have Disa here at home. Keep it in water, good water that is.
prankster d
Marilyn , How do Odonts and Oncids fit in? CAM? or Non-CAM?
fluer
I do not have any disas.
marilyn001
I grow Disas with my cactus! I started with seeds a few years ago and learned as I went along. Disas keep cool by transpiration and evaporative cooling. When the air temperature is high (above 70F), the humidity must be low enough to permit essential evaporative cooling. Disa tripetaloides
simply folds its leaves upwards in hot, humid weather.
Fleur(Tasmania)
Disa come from the top of Table Mountain, wet, and cool.
bmtorchids(Barbara in Sunny California)
Which Disa do you have Marilyn? I now only have a Kirstenbosch Pride.
marilyn001
As far as I know, many of the Oncidium group are CAM +ve plants. Certainly equitant Oncidiums and mule ear Oncidiums are so.
bmtorchids(Barbara in Sunny California)
I first kept it in front the cooler, it didn't do any thing, I moved to the warmer side, and it is budding.
marilyn001
I have found that rainwater or melted snow is the best water source. Of course, I fertilize the plants but weakly, weekly, with flushing of plain water the day after feeding.
bmtorchids(Barbara in Sunny California)
Marilyn, I use RO water on my Disa. I was told not to feed but once in a long while.
marilyn001
Disas seem to respond to daylength. D. tripetaloides flowers first for me followed by D. uniflora and hybrids such as D. Diores and D. Watsonii.
marilyn001
Disas do respond to feeding when they are actively growing. Be sure to include iron chelate or use a fertilizer with chelated micronutrients.
bmtorchids(Barbara in Sunny California)
Those two are old crosses, are they red?
Carol Holdren(Southeast Florida)
BTW one of our club members has a RO system for sale. w/55 gallon barrel half price. Just in case anyone is interested. Let me know and I'll give you her phone number.
bmtorchids (Barbara in Sunny California):
Marilyn, if I use Dyno gro, will it be ok?
marylois
It is no surprise to me that the greater share of my most robust growers are divisions from GOOD growers.
KB Barrett
So, I should say Hi to Ed, Lois, Barbara, Marilyn (who I haven't officially met yet) and who else?
nodosa
Barbara - our local nursery supply has several kinds of sphagnum. We take Canadian or US (Wisconsin/Minnesota) by choice. Comes in 4 cu ft bales to us. Just got 12 this week, so I know the new crop is in. We give it a gross cleaning, then pack it in five gallon black nursery cans. These are
submerged in 5 gallon pickle buckets containing surfactant and a little seaweed extract. After and hour soak, we pull the nursery cans up and hang their drain holes on the lip of the pickle bucket. After the cans drain pretty well, we dump the sphagnum into bit bus trays and fluff it. From there, we pot it out. No crock in 38's - vacuum formed trays of 38 small pots, but a few styro peanuts in the six packs - about a 4 inch vacuum formed pot in sheets of 3 six cell units.
marilyn001
We did a society experiment a few years ago, with a flask of Phals. These were randomly given to about a dozen members who grew them in the same five different media. The main difference was growing conditions. One grower had huge plants with flowers long before everyone else. Another grower lost them
all. Mine. puttered along. Given the randomness of the seedling distribution, I find it hard to believe that one person got the pick of the litter and the rest of us, the runts. There is a lot going for good culture.
KB Barrett
Lois, I'll agree with that statement about robust growers. I have a Acsda. Princess Mikasa which has bloomed for me successfully for 2 years now in spite of my care. This plant had roots starting off of old dried up roots when I bought it... kinda refused to die.
bmtorchids(Barbara in Sunny California)
That sounds like a major production.
bmtorchids(Barbara in Sunny California)
Kathy do tell where did you buy that Ascda?
marilyn001
Glad to hear seaweed fertilizer is still in fashion.
KB Barrett
Larry at Orchidanica.
marylois
You're doing something right, Kathy. The point I'd like to make on "runts" is one needs to make the decision within a year or two and not spend years of time, effort and space on the one going no where. Like Marilyn says, give it to another grower (poor greengrowers). We have a lady with a cool
house...she gets lots of my mistakes.
nodosa
Marilyn - I don't know about fashion. I do think you need to have a bit of "soft" food available immediately when repotting. Doubly important when bringing seedlings out of flask. About the only alternatives are seaweed and fish emulsion. I'll take seaweed any day. Matter of fact, if you are
concerned about iron and other minerals in your mix, try some green sand. Straight off the sea bottom, but it does a great job in boosting minerals.
KB Barrett
Marilyn, don't you think there are good plants and bad plants? Maybe they didn't start out that way, but somewhere in their handling they just weren't allowed to thrive. I speak in general of nursery products, such as what you'd get from Nurserymans' Exchange etc. I think this generally holds true with plain old garden plants, as well as orchids.
marilyn001
We covered quite a bit of ground tonight. We may even have some new converts to Disas! Twas good discussing orchid culture with you. Good night all.
bmtorchids(Barbara in Sunny California)
I agree with you Lois, only when you are new at growing orchids, all the nice people give you seedling and freebies, you thought WOW, how nice, but years later they are still seedlings.
KB Barrett
I'd tend to agree with Lois, get rid of the dead weight. I've spent too many years in my yard trying to make some plants work when they just plain didn't wanna grow.
nodosa
Nite, Marilyn
marylois
hahaha- yes Barb, but as a newbie, you appreciate ANYTHING - and truth is, it's good practice stuff...and sometimes the newbie shows you up by bringing back a blooming plant! *LOL*
KB Barrett
Night, Marilyn! Good to talk with you at last.
Fleur(Tasmania, the Apple Isle.)
Good night Marilyn.
bmtorchids(Barbara in Sunny California)
Ed. the seaweed don't they have too much salt?
marylois
Nite Marilyn - again, apologize for tardiness -- I believe your subject has a few more discussions left in it!?
bmtorchids(Barbara in Sunny California)
Good night Marilyn, thans for the talk.
marilyn001
Some of the work we are doing is pointing to possible reasons why we may get runts. All I will say now is that when planning a cross, make certain that the seed parent is in tiptop condition. Seed parent condition does affect the progeny from day one.
Fleur(Tasmania, the Apple Isle.)
At least a few more sessions left in this topic I would say.
nodosa
Barbara - seaweed is sold as an extract of kelp, not as actual weed. The process turns the actual seaweed into a disgusting dark green yuk, but if does supply what we call "soft" nutrients: no chance of burning. We like these for plants on the move.
marilyn001
This is a biggg subject and worthy of several more sessions.
marylois
Marilyn - you say seed - most scientific minded folks say seed...yet many books, and Wildcatt say pod....seed is sure confusing when used with pollen...to me anyway.
kawacym
Seaweed works better on seedling cymbidiums better that mature plants, really gives seedlings a boost.
bmtorchids(Barbara in Sunny California)
Yes, I love to try Masd again.
nodosa
I'd like to say a few words for runts - having been one for all of my 39 years. When we select just the biggest plants we're heading toward just that - big plants. We need to work with some of the smaller, more compact members of a cross to get plants that are friendly to smaller culture areas such as window sills and under lights. We like them in the commercial trade, too, because they can be shipped and handled more easily.
KB Barrett
Barbara, You'd better check with Dean before you try Masds again! He'll needa rest after the Kitchen before tackling a new wet wall in the GH.
nodosa
Lois - I think the on plant container for orchid seed is properly called a capsule.
marilyn001
I say seed parent as opposed to pollen parent. We could also say mother plant.
marylois
Yes, Ed - but is a smaller plant of a normally larger plant what you select, or a robust member of a small growing individuals?
Fleur(Tasmania, the Apple Isle.)
Ed, a man after my own heart, big is not always better. I much prefer small and dainty.
KB Barrett
Ed, is that how you select for Phals with shorter spikes? (one of your endeavors) Just get small plants and cross breed?
nodosa
Lois - it depends. In Phalaenopsis, choose the roundest leaves regardless of relative plant size.
marilyn001
There are runts and there are compact plants. There is a difference and I believe the difference is vigor. I raise compact catts so vigorous that they bloom 3x a year. I wouldn't call them runts.
nodosa
Kathy, we love short spikes on Phals. Especially the first two internode sections. We can chemically shorten these but the procedure is not cost effective.
marylois
pod/pollen may be pedestrian, but it is also graphic....yes - have heard "seed capsule" (and not on "Invasion of the Bodysnatchers" *grin*) -- and mother plant, of course. Better to know all the derivations...but pod=seed had me going for a while -- was thinking seed=pollen.
bmtorchids(Barbara in Sunny California)
Kathy, you are right, I may have to replace the cooler this year, it's been 5 years.
marilyn001
Must go all. Had a long day. Nite Lois. Take care. Look forward to receiving a transcript. Bye!
KB Barrett
And I grow robust plants so hard that they barely survive my ministrations to bloom yet one more year!!
nodosa
Thanks for the good session, Marilyn. My apologies for late arrival!
marylois
Oh, I agree! Love the mini's in every species - just not at the expense of vigor.
marylois
Nite, Marilyn - thank you - and will send the transcript ASAP...have to "order" them from WBS whereas I can get by email request at ICS. Have a good night.
Fleur(Tasmania, the Apple Isle.)
Good night Marilyn, and thank you so very much for a informative session.
- 30 -
Presentation Comments
Nice interested group this Wednesday night and much of interest!! Thank you, Marilyn. Good news! There are avenues not yet travelled buried in the paper upon which last night's discussion was based, and Marilyn has graciously offered to come back late this summer for more sessions!!!
From: Marilyn Light
Gradually emerging from a haze of work, projects, paper writing and the lot. Trying to focus on writing my book but haven't yet got the impetus. Too many things intrude, like warm summer days in May!, moving plants in and out and in again because of frost risk and out....You get my drift.
It seems to me that the May 14 session opened a door on the very interesting topic: learning to distinguish orchid runts and discovering why an orchid sometimes fails to thrive.
Does the difficulty arise from something the hobbyist is or is not doing correctly? Is the plant diseased or does it suffer a nutritional deficiency?
Does the difficulty arise in the plant itself?
I suppose this is the million dollar question and a major part of developing an orchid-colored thumb is in is in learning how to distinguish between the two situations.
Pot plant producers are making major strides towards selecting plants (such as Phalaenopsis) which grow quickly, bloom readily and profusely, under a variety of conditions.
I look forward to developing this line of thought further with orchid safari members.
Best wishes,
Subject: Re: Presentation Comments
Marilyn
