How to Hybridize, updated
David
PREAMBLE
Many of the methods proposed by members for producing seeds such as: using a cat’s whisker, a cactus spine or a cotton bud – would be more at home in a J.K. Rawlings novel, just waiting for Hermione to wave her wand and cast her magic spell! Magic doesn’t really work with Adeniums. You need to be scientific!
Hybridizing consists essentially of three elements:
1 The emasculation of the female parent to prevent self pollination
2 Transfer of pollen from the male parent to the stigma of the female parent
3 Labelling and recording the cross.
When I first attempted hybridization in Adeniums I found considerable difficulty in locating both the pollen and the stigma. I would have found my photos posted on the group invaluable. I had extensive knowledge of hybridizing in both orchids and rhododendrons. The Rhododendron Group of the Royal Horticultural Society asked me to write an article on how to hybridize Rhododendrons for publication in their year book which they published. Even with this experience I found information on how to hybridize Adeniums almost non existent. Dr. Mark Dimmitt kindly sent me a long text message of how to do it and this was extremely helpful, but from thereon I had to teach myself.
Tweezers and probes should not be a problem. Just look up Dental Suppliers in the Yellow Pages and telephone one of them your requirements, give them your credit card number and the package should arrive very quickly. If you cannot find a dental supplier most large small-tool and radio ham shops stock all sorts of tweezers and you should be able to find something suitable there. The construction of a probe would not be a problem for any amateur handyman. Just obtain a short piece of stainless steel wire, place the end on a vice or small anvil and hammer a short flat. You can then file and sandpaper to the shape you want.
Non scientific methods may work to give seed but you will have no idea if the cross is what you want, a self pollination, or even from pollen from a previous cross still left on the pollinating tool! One member said what a lot of work was involved in the scientific method. This is just not true, the system takes longer to describe than to perform. I usually arrive in my Adeniums between half past six and a quarter to seven in the morning and examine them very carefully to see if there are any crosses I would like to make that day, if there are I make notes. The young man who looks after my Adeniums arrives at seven o’clock with a pot of coffee. After coffee my assistant makes the crosses whilst I write up the note book and write the labels. We regularly have ten crosses completed in under half an hour.
I keep some big Adenium obesum plants just to produce seeds for rootstock. I asked Rudy, my assistant; to hand pollinate some of them in just one hour, without notes or labels. He pollinated 33 crosses. Adenium obesum is usually easy to pollinate and you can expect around a 50 percent take. They are also generous with seed production usually giving around 130 seeds per double pod. So this should produce around two thousand seeds in one hours work. How many seeds do you need?
By the way, on checking my records, our success rate has improved from around 10 per cent to 20 to 30 percent. This is not that we are improving our pollination techniques but rather that we have learned which plants are seed (♀) sterile and no longer waste our time putting pollen on to them. Dr. Mark Dimmitt once told me he thought Adeniums were evolving towards being dioecious i.e. male and female on separate plants. I am beginning to agree with him.
England’s most prolific Rhododendron breeder, Lionel de Rothschild was famous for his remark on the first flowering of his hybrids. Seven years anticipation and a moment’s disappointment or ecstasy. It is exactly the same with Adeniums. I would recommend all our members to experiment with hybridizing, it is great fun and the wait is usually only just under one year not the seven years for Rhododendrons. But remember, if you want to produce something superior only cross the best with the best.
I hope that this group will soon form The International Adenium Society which amongst other things will be responsible for registration of Adenium Hybrids. The registrar when appointed will require knowing the exact parentage of any hybrid you want to register, you need to be scientific.
When pollinating please do not use a small paint brush as this is very difficult to sterilize. It can be done with alcohol but it is difficult, if you use a brush it is quite possible for a total pollen mixture to be applied to the female parent possibly causing a lot of confusion when the resulting seedlings flower!
How to Pollinate Adeniums
If you are serious about pollinating Adeniums you will need some basic equipment:
1 Dental tweezers for trimming the flower after stripping off the petals and also to remove most of the anther cone (Claudius Ash, Surgery No.13, catalogue number 6242 5013) or similar.
2 Simple dental probe (stainless steel Cotterill No.1) this has one horizontal flat surface, ideal for extracting the pollen from the anther cone and the other end is turned through ninety degrees and beautifully polished, ideal for pushing the pollen on to the stigma. These two items (or similar) can be obtained from any dental supplier or even your local friendly dentist may let you have them. Mark Dimmitt recommends using a small scalpel or small artist’s razorblade knife with a narrow blade but I find the dental probe more convenient.
3 Note book, preferably hard backed, to keep a note of the crosses and the dates of the cross.
4 Propelling pencil 0.5mm for keeping the notes
5 Rubber eraser for corrections
6 Small tie on labels to identify the cross
7 HB ordinary pencil for writing on the labels (the propelling pencil gives print too narrow and can soon become illegible)
8 Pencil sharpener
9 A thin metal 12 inch ruler, for ruling columns in the notebook and also to use as a book marker. It is also used for measuring the diameter of new flowers. (This is kept in the cross book)
I keep the other ‘tools’ in a small pencil box on top of the notebook together with a pair of special high powered, half eye reading spectacles.
VISION
If you are under 40 years old skip this paragraph. Pollinating Adeniums is an extremely delicate operation and you need excellent close up vision. As a retired optometrist here is what I would recommend. At the age of 40, even if you are emmetropic (i.e. have perfect distance vision) a pair of inexpensive, ready-made, half eye reading spectacles of +2.00 will be useful or possibly essential. If you are aged 50 then ask you optometrist to give you an especially high reading addition of around +3.00 and over the age of 60 you will need +4.00 or +4.50. Also request your optometrist to check you eyes muscle balance (I am sure he will have already done this) and if he finds any significant exophoria then I would suggest he prescribes for you a small amount of base in prism to avoid getting a headache when undertaking this very close detailed work.
POLLINATING
This is difficult to describe and much easier to explain with photos. So I have taken some close ups and indeed some extreme close ups and hope they will be useful:
Photos:
Figure 1 Tweezers & probe
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PREPARING THE MALE FLOWER AND EXTRACTING THE POLLEN
Remove the top four petals (pull them off with your fingers)
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Trim around the anther cone with the tweezers; do not use scissors as this could transfer any virus infection.
A Close Up
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Grab the base of the anther filaments firmly with the tweezers then gently pull them off with your fingers. (If you don’t do this, they can very easily knock the pollen off the probe)
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Anther
cone
Pollen Flower Awaiting Removal of 1 Strand of Anther Cone
The cone is not solid; it is composed of five strands to allow access to the pollen by an insect’s proboscis or with a probe.
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One Piece of the Anther Cone Removed with Tweezers
The pollen is at the apex of the cone. The stigma or receptive surface has a flattish top which is non-receptive so that self pollination cannot take place. The receptive area is the shiny curved surface just below this. Most Adeniums are self sterile and will not set a seed pod if self pollinated.
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This shows where to place the dental probe in order to extract the pollen.
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This shows the extracted pollen.
This is just Adenium obesum
which gives a lot of pollen. The more complex hybrids frequently have very
little pollen,
so you need to very careful to extract every grain.
Indeed some of the more complex hybrids are completely pollen sterile. You
will soon find out which they are!
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PREPARING THE FEMALE FLOWER
AND POLLINATING
Prepare the flower exactly as for extracting the pollen - using tweezers remove four pieces of the anther cone - but leave one on. If you remove this last one frequently everything comes out and you need to start again with a new flower - if you have one! Make certain all the pollen has been removed to avoid any possibility of self pollination. As I said before the receptive surface is the white donut shaped curved area below the flat top.
A close up of the
stigma, the receptive area
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Applying
pollen 
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Pollen applied a little too low
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Pushing pollen to the stigma
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Pollen pushed to the correct receptive area -- pollinated!
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Write the cross in the note book and apply a label IMMEDIATELY – It is remarkable how quickly you can forget exactly what you have done!
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If you are expecting any rain within the next 48 hours and are working in the open air, it is prudent to fold the top of the remaining flower petal over, to protect your work from direct sun and rain.
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With any luck a double pod will form, if nothing has happened within two weeks nothing will. My experience is that only around ten percent of crosses will form seed pods.
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This shows a pod forming on a white Adenium, the pod is green and shows no pigment
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After about two
months, protect the pod as shown. This is net curtain material stapled
over the pod. Other members have recommended using panty hose. The
pods usually ripen and split after around 12 to 15 weeks. This is very
important as the seeds have a pappus or ‘parachute’ at each end and when the pod
splits they are likely to blow away very quickly. 
Seed showing the pappus at each end. These should gently be pulled off to prevent the seeds from blowing away
Seed Pod NOT Protected, seeds about to blow away!
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Happy hybridizing – it really is a most rewarding hobby!
David Clulow in Cojedes, the Mango State of Venezuela