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There are now many ways in which orchids are
propagated, - its not just strictly for the birds !
Commercial nurseries will use mass production methods
to reproduce a choice variety of either a specie or
hybrid plant, the favoured one goes by the name of...
Meristem culture, this laboratory technique involves
the mass tissue culture of the growing meristem tip from
within the new growth of the plant concerned, the
nucleus of cells derived from this small sample of
tissue or grown on in flasks on nutrient gels.
The result of this is the successful production of
any number of plants, all identical to the original more
or less, and that is how excellent plants become
available to us all at remarkably low prices.
However in nature initial fertilization of the orchid
flower must take place for the seed pod to develop, and
this article will focus on the principle of natural
fertilization (well almost) and propagation.
An insect when pollinating a flower usually does so
by collecting the pollen sacks from one plant (a forced
occupation as the pollen plant by various clever means
deliberately sticks the pollen sacks to the insect as it
departs) and depositing them on the stigmatic surface of
its next orchid flower as it strives to collect its
reward of a little nectar.
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Man can do the same thing, usually with the
aid of a toothpick and the two pollen sacks seen
on the left are about to be deposited onto the
stigmatic surface of the pod parent plant where
they will adhere, and the minute pollen grains
will embed themselves into the sticky bed and
nature will begin to take its course.
In a few days, providing the seed was viable,
the flower will shrivel and the column will
swell to enclose the pollen saturated area, the
stem of the flower will begin to swell and a
seed pod will develop .
This seed pod may remain on the plant for
several months until it is ripe, it is important
that the pod is harvested before it splits as
the seed may be lost or spoiled.
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Not all seed pods will have viable seed.
In order to ensure that no more time is
wasted on them a sample of seed will be
examined, they are so minute that a microscope
is needed to see them properly even after they
have been soaked for a few hours in a sugar
water solution, which makes them easier to
study.
On the right, you can see how primitive an
orchid seed really is, it consist of a single
cell, which is contained within an open a
fibrous network, and at this stage is extremely
underdeveloped.
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Symbiosis
In nature, the orchid seed will only grow when
exposed to a microscopic fungus, which helps to break
down the sugars and nutrients for the seed.
The seed cannot survive without this symbiosis taking
place, but as it is a hit and miss affair in nature
propagation in the hands of man has resulted in an
alternative and more viable method.
Firstly, as the orchid seed which has been contained
in a sterile atmosphere within its seed pod may be
contaminated by the wrong airborne fungal spores, and as
it is about to be introduced to another sterile
container ( a flask) it must be thoroughly sterilized to
avoid being contaminated within its new environment.
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A nutrient gel is prepared and sterilized,
this will eliminate the need of the primitive
seeds dependence on symbiosis.
The gel is allowed to set inside the flask, and
the sterilized orchid seed is sown thinly across
its surface.
Hopefully the seed sowing will have been
successful and in a little time will germinate,
and the surface of the gel will become covered
with a mass of round green spheres, these are
called protocorms.
These miniature orchids will be sown again
into new flasks which may contain a stronger
medium, and again this is done in sterile
conditions, eventually from the thousands of
protocorms originally sown only around 25/30
will be sown into the final flask.
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The task of replating (reflasking) may be done again
and again as the plantlets mature and grow, and
eventually they will become large enough to be pricked
out and sown in regular orchid compost to continue and
grow into flowering plants.
From seed to mature plant can take from three years
upwards.
Propagating by division.
Orchids may be propagated by division, those whose
growths are Sympodial, (that is one new growth appearing
from the base of an older growth) lend themselves easily
to such an exercise; taking a sterile blade, cut through
the rhizome leaving ideally at least three growths on
each portion, this can be done at any time, providing
the plant remains undisturbed in its original compost
until the next re-potting takes place, when you should
have perfect divisions.
On Monopodial orchids (those whose new growth comes
from the centre of the plant, the exercise is a little
more complicated, and should not be undertaken lightly.
Vandaceous orchids are of this type, and when a plant
has reached a size too big for you to cope with, it may
be cut down, providing that there are sufficient aerial
roots on the cutting to make it viable, which can then
be re basketed to grow on, the old stump should not be
thrown away, as it may well produce several new growths
from below the cut, and these may be eventually removed
to form new plants or left as a splendid clump.
Phalaenopsis orchids if damaged may produce several
new growths from beneath the ruined crown, or a little
keiki paste may be added to the nodes of a flowering
spike to encourage the growth of plantlets, sometimes
this happens without encouragement, and when the
plantlets have enough root they may be teased from the
parent and potted up.
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