Welcome and I’m so glad to see you guys today. Thank you for inviting me.
I’m sorry to use this title but don’t you think “Propagation” is kind of boring?
And truly, when we are talking about propagation we are talking about
reproduction. And reproduction starts with sex right?
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So I’m going to start with basics so we are all on the same page. We all know
that sex starts with a mommy and a daddy. And if considered on a strictly
basic level, the reason they have sex is to have children in order to continue
the species.
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But if the mommy and daddy are too closely related like brother and sister or
even first cousins then there will be less genetic diversity and the offspring will
be less viable, weaker, and mutations are more likely to occur– especially if
close relatives repeatedly reproduce. Hence all the West VA jokes.
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So lets take this to the plant world. And we start with the history of plants
through time. Plants began as one celled organisms that gathered together
and something called blue-green algae was formed. This reproduced by the
cells dividing but this basically created more cells that were clones of the first.
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Then the mosses arose in the historic record. Mosses do have male parts and
female parts. The male cells must swim through a water layer to reach the
female parts. Then the plant will produce another organism which you see
here. These organs produce spores which are spread to create new moss
plants. However, this is a plant fertilizing itself which means it is the same
genetic material and it relies on moisture and chance to happen.
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Next come the ferns.
Ferns are really just advanced mosses with vascular systems. The fern will
produce spores which is what you see here in this cinnamon fern on the left.
Other ferns will grow these on the bottoms of the fronds. If these spores fall or
are blown into a suitable spot, they will grow into a gametophyte which is a
sexual intermediate plant. This intermediate plant will then grow male and
female parts. The male cells will then swim to the female and if they meet,
they will then produce a new fern from the gametophyte. Still pretty iffy, needs
water and still basically the same genetic material.
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The next big advance is the gymnosperms. These are the conifers.
Now conifers have two types of cones. Male cones and female cones. And
what was it that made the conifer so special? It’s the first sexual reproduction
with genes from two different contributors. And they do this by producing
pollen. And for those of you who have lived at the beach, you know it can be a
lot of pollen.
Anyone know why so much? The pollen is spread by the wind. And those
trees need a lot of it in the hopes that some might find its way to another plant
of the same species. But the tree also doesn’t really want the pollen to land on
its own female cones so it has several methods to prevent this. Either the
pollen is released at a different time from the opening of the female cones. Or
maybe they are in different places on the tree.
But there is still a pretty large element of chance in this type of reproduction.
Hopefully, the wind will carry enough pollen to a tree of the appropriate species
and it has to land in the right spot. And the tree has to produce a huge
quantity of pollen in order to ensure something gets where it needs to be. And
this creates a large resource drain on the tree to produce so many high protein
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particles.
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The next big advance is the gymnosperms. These are the conifers.
Now conifers have two types of cones. Male cones and female cones. And
what was it that made the conifer so special? It’s the first sexual reproduction
with genes from two different contributors. And they do this by producing
pollen. And for those of you who have lived at the beach, you know it can be a
lot of pollen.
Anyone know why so much? The pollen is spread by the wind. And those
trees need a lot of it in the hopes that some might find its way to another plant
of the same species. But the tree also doesn’t really want the pollen to land on
its own female cones so it has several methods to prevent this. Either the
pollen is released at a different time from the opening of the female cones. Or
maybe they are in different places on the tree.
But there is still a pretty large element of chance in this type of reproduction.
Hopefully, the wind will carry enough pollen to a tree of the appropriate species
and it has to land in the right spot. And the tree has to produce a huge
quantity of pollen in order to ensure something gets where it needs to be. And
this creates a large resource drain on the tree to produce so many high protein
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particles.
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So obviously what was needed was a surer way to get pollen from one plant to
another of the same species. And that brings us to the Angiosperms- plants
with real flowers.
The first flowers were probably pretty simple. But over time they became more
elaborate and intricately designed with only one purpose- to attract something
that would pick up the pollen and take it to another plant.… And in the process
avoid being fertilized by its own pollen.
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When looking at flowers, there are a number of ways they are designed.
There are male and female plants that have male flowers on one plant and
female flowers on another plant. (ilex, ginkgo, kiwis). There are plants that
have male and female flowers in separate flowers on the same plant (Squash).
And there are plants with both male and female parts in each flower like this
hibiscus.
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And then there are some flowers that are pretty surprising because they aren’t
really flowers at all. Dogwood, where are the flowers on this dogwood.
Here’s a modern hydrangea. Where are the flowers? Here’s a modern lace
cap. Both of these were massively hybridized in order to take advantage of
the sterile flowered pompoms or the real flowers. This is an antique
hydrangea from before hybridization took place. You can see some pompoms
and some lacecaps on the same plant.
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There are a number of possibilities here. Birds, Bees, Moths, butterflies, flies,
beetles, and bats.
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Now I said there was only one purpose for flowers and that is to get something
to come grab the pollen and take it to another flower of the same type but
different plant so its genetic material moves.
New research is showing that flowers do more than just look good. The
design is such that the pollinatore must pick up or drop off pollen. Nectar is a
reward to get the critter there. Now research has shown that many plants
actually produce a small amount of caffeine in their nectar as well. Free coffee
and donuts… Hello.
Other plants have polllen with an electrical charge and the insects like bees
are the opposite charge so they are attracted. Tomatoes and blueberries must
be vibrated for theme to drop pollen.
But what if the pollinator comes repeatedly to a flower that has already had its
nectar consumed. We now know that the electrical charge changes over time
so insects don’t repeat visit or the color changes, or they close up.
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But even with these specialties, pollination is still a bit chancy. A critter has to
just happen by at the right time, happen to get pollen on itself, and then
happen to take the pollen to another plant of the right type. So plants began to
specialize. First they produced nectar. For the insects, pollen provides protein
for cell construction and nectar provides sugar for energy.
But then flower designs started to change in order to specialize for a specific
pollinator.
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The reason I have gone over all this, not only because it is so interesting, but
is because after the plant is pollinated, it produces seeds and that is really
what we are interested in in this class. You can produce new plants by
planting the seeds.
Seeds have four requirements, water, light, oxygen, and temperature, of which
amounts needed are determined by the plant variety.
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OK that’s it for sexual reproduction. Now lets move on to asexual
reproduction.
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For a plant there are still advantages by producing new plants through asexual
reproduction. These are clones, if you will, of the original plant. It makes a
larger plant which allows it to gather more moisture, nutrients, etc. If some of
the plant is killed for some reason, its more likely that some will survive. If it is
attacked by insects, then there is more likelihood that some of the plant will still
be healthy to support the extra stress.
And for us humans, it provides us with another way to get more plants. And I
want to take this moment to add if you have a named plant, it must be
propagated by one of these methods rather than through seeds. Only a clone
of that original plant has every attribute of the parent. If seeds are gathered,
then likely they won’t be exactly true to the parent.
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Terminal bud- the bud at the very end of the branch
Lateral Bud- a bud not at the tip of the branch
Node- the area where the bud originates on a branch
Internode- area between the nodes
Stem- the main support (trunk)
Leaf- food producing organ
Petiole- the small stem that holds the leaf onto the stem
Root- the underground structure that supports the plant, stores food, and
collects water and nutrients
Root Cap- The covering of cells on the tips of the roots that protect the apical
meristem
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Division is the first method we will discuss. This is a matter of digging up the
plant and cutting them apart so there are tops and roots together.
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Small plants grow out from the “Mother” plant. Cut those off and plant them.
They will make a new plant.
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Place a leaf into sterile soil and it will grow a new plant. Some will grow at the
petiole and some will grow from cut veins
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Stem cuttings are done with a lot of different plants. There are four different
types of cuttings that can be done. Herbaceous is done on herbaceous (nonwoody) plants. Softwood are collected from woody plants when the new
growth has just finished growing. Semi-hard wood the new growth wood is
just starting to develop bark. Hardwood is this years wood that is at the end
of the season so it has fully formed bark. Different plants do better with
different types of cuttings. Look it up to find which plant wants which.
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