OrchidSafari ARCHIVES*

The Trembling Toothpick: Basic Hybridizing
by Ed Wright

For too many years, orchid breeding has been considered a secret art, passed on from master to apprentice with incantations and secret words. Part of this may even be true, for I have known hybridizers who followed American Indian rituals, the Hawaiian moon calendar and the Aztec sun calendar in their programs. Despite these dark methods, we can learn rather quickly the basics of hybridizing and can see ways not only to breed better orchids but to buy better orchids for our collections.

In this session, we'll study the mechanics of the orchid reproductive system. We need to know what goes where to do which before we can begin to study blood lines and pedigrees. With this in mind, let's plan to do an orchid dissection in cyberspace. To participate fully, have the following items convenient to your computer at Wednesday's session:

A couple of orchid flowers, at least one of which you are willing to destroy. When you cut your 'destruction' flower from the plant, leave as much stem as possible. The flower should not be wilted, but it need not be show quality or exhibition fresh. I'd recommend using a Cattleya bloom if you can manage it because the parts we want to examine are large in that genus. Phalaenopsis blooms are almost as easy to see, and will certainly work. Let's not try Paphs, Masdevalias, Pleurothalids, or unusuals right now. What we want to do is clearly define the working parts and talk about what purposes they serve in producing and reproducing orchid plants.

Three or four toothpicks will be needed. We prefer the kind with one flat end, but the double rounds can be used.

Room enough to lay out plant parts in sequence as we work. Like Humpty Dumpty, they can't be put together again, but it will help your study and especially your review if you have them in the same sequence as your notes.

A razor blade. For safety, use a single edge blade, but if you must use a double edge, put a piece of adhesive tape over one edge.

A pencil and several sheets of note paper. We're going to name and observe parts, so you will want notes for referral. Pencil will be better than a pen because a smear or two of plant sap is inevitable and ball points don't like writing over plant sap.

What we will study can be easily seen with unassisted vision. It is good practice, however, to use a hand lens or magnifying glass for all such study. Detail will be clearer and definition (the separation of similar tissues) will be facilitated with a glass. Nothing fancy here, a fresnel lens or dime store reading glass is ample.

Finally, we will need lots of questions, summaries of things you have tried or would like to do and discussion of flasking, flasks, media and techniques. Yes, we'll even borrow from the OLD and consider Jello, if that's what you want to do. Main point is, let's talk about hybridizing and learn together about one of the most interesting areas of orchid culture.

Ok - look at your Phalaenopsis head on. The column, fleshy protuberance in the center, is where most of the action is, but let's get some debris out of the way. Remove the two petals - ear looking pieces at 9 and 3 to the column. Put these down on a flat surface.

NOTE: A numbered diagram was previously furnished participants.

Now remove the dorsal sepal (at 12) and the lateral sepals at 4 & 8.

Note how the pieces resemble a botanical drawing when they are put on a flat surface in "plant position". Now remove the lip as close to the column as possible and add it to the "drawing".

The remaining piece has several important parts. The "nose" is the anther cap, the fleshy white or light section is the column, the ring that held sepals and petals is the transition, and the green "stem" part is the ovary. Note the faint creases in the ovary - they are divided into three areas.

Look closely at the "nose" area and you will see a bird's head. With a toothpick, carefully lift the "beak" and you will dislodge the anther cap and the pollen.

Leave the anther cap in place a few moments and look at the cavity where the pollen developed. This is part of the septum that divides the pollen from the stigma - the socket of shiny material just behind the septum.

At the lower portion of the septum are two denticulae or teeth. These serve to pull pollen from the pollinator and retain it on the stigma. Note the position of the denticulae. They tell us to place the pollen well forward on the stigma, as opposed to down in the throat of the stigma cavity.

Now, let's place the two pollen grains on the stigmatic surface, up near the front and right behind the denticulae or teeth. We want to practice putting pollen here because it is the preferred natural area.

Next, take a razor blade and cut the whole piece in half the long way. Have the top of the blade centered on the dorsal sepal area and cleave away. Try not to bleed on your keyboard. The pollen should be on the shiny surface, underside of the column, just behind the septum and just behind the denticulae.

Look closely at the halved stem/transition/column because it is going to tell us some interesting things. First, by placing the pollen on the stigma, we have pollinated the bloom - not fertilized it.

Go back to the stigma. The pollen grains will begin to grow on the stigma and will form pollen tubes that will transit all the way down through the column, transition zone and into the ovary to fertilize the ova there.

Let me try to finish the basic Phal cycle, then we'll discuss other things as long as anyone wants to stay and chat. When the pollen tubes reach the ovary, they fertilize most of the ova in a normal sexual union. In a few cases, however, a double union occurs. These ova grow very rapidly, then die and decompose into a nutrient broth that supplies food to the remaining seed. This is the orchid equivalent of endosperm, I suppose. Orchid seed do not store any nutrients when the pod dehisces. Dehisce is a wonderful term: it refers to the splitting open of the pod to dispel seed, but it comes from roots that mean "to yawn". Great descriptive label!

Back to the ovary. As the seed and supporting tissue develop, the ovary expands enormously and it is then that the pleats we saw so faintly will provide the additional tissue to expand the seed capsule to many times the stem diameter

What do you call the lumps on the surface of the lip?

The lumps on the lip are called callus tissues and are very prominent in both Phals and most oncidiums. Just behind the callus, as the pedicle begins, is a region that emits scent or other attractant. Not well developed in Phal and Den, quite pronounced in Catt and Aerides.

Also, not to be dense, but I don't see the ovary divisions. This is the "stem" which connects to the stalk? Are the divisions running longitudinal or circumferential? Pleats are longitudinal just behind the transition area where the sepals and petals were attached. There are many of them, but three will be prominent enough to see at this stage. Next time you're near a standard size Cattleya, look at the stem area and you'll see them plainly. On a Vanda, you'll hardly see them at all.

Are the denticulae the hook that used to be under the anther cap?

There should be two "small hooks"; they are the denticulae we discussed. Their purpose is to pull the pollen grains from the pollinating insect and deposit it on the stigma.

How does the pollinating insect get to the pollen? I had to forcibly pull up the anther cap!

When the potential pollinator enters the flower in search of nectar, the lip is articulated downward, exposing the basal area behind the callus zone. As the insect backs out of the flower, the lip applies continual pressure, keeping the insect's back against the under surface of the column. As the insect exits, the "beak" of the anther cap is pushed outward and the viscid disk cements to the insect, usually in the "head or shoulder" area. In about 3-5 minutes, the "stalk" of the pollen erects and the anther cap is dislodged by the wind. The stalk then positions the pollen to be deposited in the next flower the insect visits. The tactile strengths of the viscid disk and the stigmatic surface are interesting. If one grain of pollen adheres to the stigma, it separates from the pollen stalk, leaving the other grain of pollen on the pollinator. If both grains of pollen adhere to the stigma, the viscid disk is pulled from the pollinator, leaving both grains of pollen on the stigma. That's pretty close figuring of relative stickiness in my book.

I see a hole down the center of the ovary.

Correct and with a modest lens, you can see little gritty beads lining that cavity. These are the ova that will be fertilized by the pollen tubes. The ova are easier to see on a Cattleya. On Catts, you will also see a false opening that ends in a sac. This is even farther developed in Vanilla, where a false septum and false stigma are positioned in front of the real things.

How long does it take from pollination to fertilization?

Lapse from pollination to fertilization can take up to 4 months. Phals run about 20 days.

I also noticed that as I hooked the pollen long threads were pulled out and then snapped. What are they?

Those long elastic threads seem to be designed to insure the pollen actually "takes". If it does not, it is repositioned for another try. In Cattleya, the pollen is on tightly curled cords and they can stretch to enormous length, relatively. In some catasetums, there is a trigger mechanism that shoots the pollen up to 30" to attach to the insect.

If you cross two very dissimilar Phals does that nutrient broth and/or double union not occur, thus causing the cross not to be successful?

I doubt it. Number one, if you stay away from Paraphalaenopsis, there really is not such a thing as "very dissimilar" Phals. Of course there is great variation in growth characteristics - gigantea, violacea, etc. It is much more likely that the pollen tubes did not survive the journey through the column and transition zone. This seems to act as a sort of a biological filter and suppresses incompatible crosses. Remember: when you apply pollen to a flower you have pollinated it, nothing more. Fertilization takes place from a few days to several months later as the pollen tubes develop and progress down to the ova. This is an incredible distance in Brassavola digbyana, so B. digbyana is rarely used as a pod parent. Same is true for Brassavola cucullata. In Epidendrum parkinsonianum, my guess is the pollen tubes take 6 months to fertilize the ova and the seed capsules take 16 - 18 months to mature. How much of the flower do you tear up to pollinate it? How much damage can a flower withstand because I have seen Paphs without their pouches in greenhouses, due to recent pollination. An accident I'm sure.

Probably not an accident. Hard to get to the "works" on a Paph with the lip in place. No reason not to remove it to do the good work. An orchid exists only to reproduce. It may damage our egos that they do not bloom to enter shows or get judged, but the sad truth is they have a singular reason for being. Bugs can eat 90% of a flower and the other 10% can still attract a pollinator. The one thing that must remain unscathed is the ovary/transition/column process.

How long does the pollen stay viable after removal from under anther cap?

Properly treated, pollen has an active life of many years. I must say Cymbidiums and the Cyp family seem to vary from this, but my hybridizing experience is insufficient to define for them. Most of the Vandaceous group, Catts, Den and Phal - indefinite.

Do Mormodes have male and female flowers. Like the Catasetum?

Many Mormodes have multiform flowers, but I've never been able to tell which is male and which female. The trait is almost universal in Catasetum, of course.

Must the pollen be removed to make the stigma active? How long does it stay viable?

The pollen and the stigma are independent. A flower can be pollinated with its own pollen still in place. The stigma remains active in general terms as long as the flower is in good condition. In practice, we prefer to use pollen from a mature flower on a very young, sometimes immature, stigma. If we are making a very exotic cross, we may force open a partially open bud and pollinate it. On plants that are notorious for difficult breeding - tetraploid forms of Oncidium splendidum come to mind - we can sensitize the stigma by swabbing it with fresh orange juice before applying the pollen.

Once the ovary begins to swell, what is the general amount of time that a Phal takes to develop the pod?

We figure a nominal 111 days from pollination to harvest on a Phal pod. They mature faster in warm weather, slower in cold. We don't harvest pods by date anyway, just start looking after so many days. When a Phal pod is ripe, the stem end will get a rough texture like an orange peel. We try to do nothing but green pod flasking because viability is so much better. The best info I've seen on harvest time for a variety of pods is some work done by Ruben Sauleda (RIO -Ruben In Orchids). This was published in the April '76 AOS Bulletin. We have the harvest table laminated and use it all the time. Again, just a guide. Actual harvest depends upon the pod.

One thing that makes day counting easy is to make a day number table. January 1 is day 1 and you number the days consecutively through the end of the year. Our cross label would read something like "6079" for 20 March, the 79th day of 1996. One can then add desired days to maturity very easily and see what date the serious looking should start.

What's the proper treatment to store pollen - freezer?

We lost the net on a question about freezing pollen. Don't do this. Cold won't hurt the pollen but sweating is deadly and cold things sweat. We use nominal 2" X 2" tissue paper squares to hold the pollen. Write the donor name and the date on one edge, turn the paper over, crease across the center and put the pollen in the crease. We then fold the halves together across the crease and fold the paper again in thirds, date showing. Fold again in thirds and you have a little packet with the date on top. We store these in little glassine envelopes we buy by the 100 at a stamp and coin shop. On the cover of each envelope we write the name of the donor and a description. The glassine envelopes are collected in small plastic bags by genus, sometimes sub-divided by color. The plastic bags are open - not folded or sealed. The whole shebang is stored in a hermetically sealed coffee keeper that has about 1 ½" of silica gel in the bottom. The coffee safe is kept on a shady lower shelf in the greenhouse. When we need pollen, the appropriate envelope is taken out and the safe immediately resealed. Since the pollen is already at room temperature, it does not sweat - ergo long lasting pollen. My mentor in the hybridizing game was Bob Betts, and Bob always put pollen in a twist of paper and carried it in his shirt pocket for awhile so it would be warm before applying it. Between us, he always chose the left pocket and I always figured a bit of Bob's heart was in each cross. The plants seemed to think so, too.

Once harvested, how long do you have before you must germinate seed?

Re time before germinating the seed. No point in harvesting a pod until you're ready to flask it. If you have to send it away, harvest it early - when the first yellow shows anywhere on the stem, pod or residual column.

Is there some kitchen science for germination? i.e., Banana Jello, or Mother Plant technique?

Jello and gelatin are not suitable for germinating seed. They contain salt, among other things. You'd be better off making a corn meal mush base (saltless) because it would be pure endosperm, though not what orchids prefer. Orchid seeds must have sugar and reduced pH. Grape jelly might work, but agar mixes are not that expensive.

How about Mother plants?

As in the very early stages of Orchid growing, the seed was sprinkled on the bark (growing medium) of another plant and it would germinate much the same as it did naturally. Well, it wouldn't have been bark - more than likely live sphagnum - but the first hybrids by Domini were almost certainly germinated by spreading the seed at the base of the mother or pod carrying plant. The purpose would be to associate the seed with mycorrhizal fungi, which is the natural way. This group of fungi produce natural sugars as a by product. Not a very effective technique as only 4 or 5 plants develop for 100,000 seeds sown. In addition, there is no way to control a fungus in a greenhouse. Natural limiting factors are missing and you might wind up with a moldy soup on all your benches.

Ed tell us about the Angraecum sesquipedale and the long spur.

Not much I can add to the Darwin story. Darwin predicted a moth would be found with a proboscis long enough to drain the nectary of A. sesquipedale, which has an extremely long spur, though not " a foot and a half" as the name suggests. That was pretty much a house bet because something was pollinating the things and a bee couldn't get off the ground with that much snoot. Sure enough, such a moth was found - Xanthopan morgani praedicta, if memory serves. Of course, this may be a much better story than it is a scientific proof, as I don't recall literature proving the moth as the primary pollinator of sesquipedale. Little item of interest: Angraecum is taken from Angraek, the Dutch word for orchid. My Dutch-speaking relatives might make something momentous of this but I do not.

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