Hybridizing, How and Why
Much of this information is useful for hybridizing
all types of plants, not just irises. The basic idea is to create an
entirely new plant by combining the characteristics of two different
parent plants. Since we will be working with irises I will discuss the
To create a new plant you take the pollen from one
plant, this is referred to as the "pollen parent", and transfer
it to the stigma of another plant, this will be your "pod
parent". Within a few hours the pollen grain will send a tiny tube
down through the style into the ovary and then into the ovules or
embryonic seeds thus fertilizing them. If the ovules are successfully
fertilized within a week or so the flower will dry up and fall off and the
ovary will begin to expand to form the pod. When the seeds are fully
mature (in several months) this green pod will turn brown and begin to
split at the tip to show the brown seeds. That is the time to harvest your
seed. Even though the seeds are all from the same parents each one has
come from a different pollen grain and different ovule so the resulting
plants will resemble each other and be somewhat intermediate between the
parents but each will be genetically different in the same manner as
brothers and sisters. All the plants resulting from seeds from one pod are
usually called "siblings".
But why do we want to do this in the first place?
Because it's FUN! There is no high like the one you get walking down a row
of flowers blooming for the first time from your cross, knowing you had a
hand in planning these flowers and knowing that no one else has ever seen
them bloom before. Before you reach the end of that first row you will be
planning how to improve on these flowers and your next set of crosses will
be underway. Some one described it as "painting with DNA". It is
a creative endeavor in which almost any one can participate.
To mimic a bee all we need is a pair of tweezers,
some small paper coin envelope or folded envelopes and in some cases a
small camel hair watercolor brush and a small bottle of rubbing alcohol.
When the pollen is ripe the stamen will split so you can see the
"fluffy" pollen. If you want to save pollen for a few days to
use on a later blooming flower simply remove the stamen with your tweezers
and store it in a small envelope in a cool dry place. Be sure to write the
name of the iris on the envelope, When the stigma begins to curl away from
the style arm and looks wet it is probably receptive. Take your tweezers
and remove one of the stamens from the pollen parent. Wipe it across the
stigmatic lip of the pod parent, you should be able to see a coating of
pollen on the sticky stigmatic lip. If pollen is plentiful place pollen on
all three stigmatic lips, if you only have a little pollen you can
probably still get a full pod of seeds by only pollinating one stigma.
Mark your cross using small paper or plastic tags and a pencil or
waterproof pen. Attach the tag below the ovary. Write the name or number
of the pod parent first then an X followed by the name or number of the
pollen parent. Record your cross in a note book for future reference.
Records are important!!
When working with bearded irises there is little chance of contamination
by bees but when working with beardless irises it is a different story.
If left alone most beardless irises will set a bee pod for every flower.
To prevent contamination use "loose buds" that are about to open for the
pod parent at least, I use them for the pollen parents also to be sure
the pollen is not contaminated. I open the bud and remove the petals and
stamens, saving the pollen if I want to use it also. By removing the
petals the bees have no place to land and it is difficult for them to
contaminate the cross. I then wait for an hour or two until the
stigmatic lip is mature and make the cross using a fresh flower for
pollen or using pollen from that saved in envelopes. If you have saved
pollen, particularly that of beardless irises, it often; s scattered all
over the envelope in just a few hours with non left on the stamen itself
I then use a very tiny watercolor brush to apply the pollen to the
stigma. If you use this method you need to carry a small bottle of
rubbing alcohol to wash your brush after each cross to kill all the
remaining pollen so you don't contaminate your next cross. Be sure you
let your brush dry thoroughly before using it again. Luckily this only
takes a minute or two. Some people are impatient and carry several
brushes so they don't have to wait. If the pollen is scattered around a
coin envelope you can loose much of it down in the comers so I use
little folded envelopes I learned to make many years ago. If you want to
make some the directions are below.
Now that we know how to make a cross the decision of what to cross is
the next and most difficult task. The most important thing is to have a
goal. You will be caring for these irises for the next four years before
serious evaluations can be made. For the beginner you will more likely
have success if you cross similar irises, pink bearded with pink
bearded, Siberian with Siberian, or PCN with PCN etc. But have a reason
for each cross such as a better branched pink bearded, a more ruffled
white Siberian or a more hardy PCN. Select your parents carefully from
the best irises available. If your goal is a better branched pink
bearded iris select the very best colored and formed flower for one
parent and the best branched pink available, even if the flower isn't
great, for the other parent. Murphy says you will get the poor flower on
the poor plant but sometimes we get lucky in this gambling game known as
If you think this is a hobby (read that addiction) that you want to be
serious about give careful consideration to your goals. To become a top
hybridizer of tall bearded irises is very difficult. The competition is
stiff for beginners. However there are not many working in the field of
MTB's or MDBs or working on some of the species groups or even on
PCN'S. In these fields you will be able to see some realization of your
goals much more quickly. Changes and improvements in Tall Bearded irises come
very slowly and in tiny increments. If you are the type to be very
adventuresome try some wide crosses, we really don't know what irises
will cross with what. We can study genetics and make a guess but there
are a lot of irises growing in our gardens that prove these genetic
guesses wrong! Be prepared for a lot of empty pods but if you get a take
on a wide cross and the seed grows. WOW! Whether it is a once in a while
thing or a serious endeavor hybridizing is still fun. There are quite a
few award winning iris out there by back yard gardeners from shot in the
dark crosses so go join the addicted pollen daubers. For more
information read Terry Aitken's excellent article on hybridizing in the
Region 13 'Newsletter Spring 1994.
Handy Folded Envelopes
Many of you may already know how to make these handy little envelopes. I
use them because when planting seed or using the pollen they can be
completely unfolded so there are no hidden comers as with regular
envelopes. They can be made from anything at hand if you are offered
seed or pollen when you are not equipped with normal envelopes. A bit of
newspaper, .an old shopping fist, I once made one from a dollar bill
when offered some rare seed. It is best to use an absorbent paper such
as newsprint so that seeds or pollen do not mold.
Step 1 - Use a rectangular piece of paper, 1/4 of an 8 1/2" by 11" paper
is ideal (4 1/4" X 5 1/2"). Fold in ½ along line E-F, folding A to C and
B to D as in Fig 1.
Step 2 - Fold both layers together (C-A & D-B) at line I-J in Fig 2. Then
fold again at line G-H to make a double fold. Crease all your folds
well. Your envelope should now look like Fig 3 with a folded flap on the
right side. If your paper is less than ideal in proportion you can make
extra folds in this step. This will make the envelope narrower so that
you can make the rest of the folds successfully.
Step 3 - Turn your envelope over so the folded flap is underneath on the
right side as in Fig 4.
Step 4 - Fold corner G to J along fold line E-K as in Fig 4 and 5 and
Step 5 - Fold corner E to point K along fold line L-G and crease as in Fig
6. Unfold part way and tuck point E under the flap to as close to K as
Step 6 - Complete the top of the envelope by folding H to M along fold
line F-N as in Fig 6. Then tuck point F under the flap as close to N as
possible. This is the same process you did in Steps 4 and 5 but from the
top down. When you are finished you should have an envelope that looks
like Fig 7.
Step 7 - Unfold the last two folds to open the envelope at the top as in
Fig 8. Insert your seed or pollen and refold and tuck the point under
the flap to close the envelope.
Contributed to the KCIS Newsletter by Carla Lankow, May 1997