Biology Plants, Part I

Hi, welcome back to www.educator.com, this is the lesson on plants, part 1.0000

When you look at the characteristics of kingdom Plantae,0006

What is definitely true about every single one of them is they are multi cellular, eukaryotic, photoautotrophs.0009

If they are unicellular, they would be in kingdom Protista, because all of them make their own food through photosynthesis.0015

They are all eukaryotic, their cells have nuclei, and there is a chloroplast, etc.0022

One of the things that really separate them from a plant like protist is the fact that they have specialized tissues.0027

Here are several examples in these specialize tissues that you would see in the members of kingdom plantae.0034

Number 1, a cuticle, a cuticle is like a waxy coating.0039

I am talking about the other cuticle here, same word but it means you have waxy coating.0050

It is oftentimes most visible or obvious on leaves.0055

There are some leaves where there is so much of that waxy build up,0058

You see they are shining and you can definitely appreciate that waxy protection.0061

What they are actually making that for is to prevent a lot of water loss.0067

That cuticle is very helpful for being a multi cellular terrestrial organism.0071

Vascular bundles, the ability to actually get water and fluids up against gravity.0078

If you think about cardiovascular system that some animals have, the cardio part means heart.0085

The vascular has to do with the blood transport, that fluid transport thorough out the body.0092

Vascular here, has that same meaning.0097

The ability of the tree to get water all the way up to those leaves up on the top,0099

that is vascularization allows them to do that through these bundles0104

within the roots, within the stems, within the branches and leaves.0108

There are two main sections, the xylem part of it is for water transport.0113

The phloem part is mainly for the sugar transport.0123

In this leaf here, it is a great example, I always use the major leaf vein here.0133

If we were to look inside of all these little passageways, in terms of water and sugar movement,0137

there is a lot of water moving in the leaf constantly, that has been taken up from the roots and going on up.0144

This is really a sugar producing factory, in terms of what the leaf is meant to do.0149

All those sugar producing cells can get sugar back into those vascular bundles within the leaf veins,0154

and transport those sugar to other parts of the plant that have cells any nourishment0162

but maybe are not doing as much photosynthesis, as in this particular part.0166

Stomata, singular would be stoma which literally means mouth, in Greek.0171

Stomata is plural, these are leaf pores.0178

They are more concentrated to the other side of leaf.0186

The way that they look, to have two cells side by side.0190

This is one stoma and this cell is called a guard cell.0199

The way they work is, when you want the stoma to be open, water is drawn into the cell.0207

Actually, the way they do it is they pump ions in, and osmosis has the water follow those ions because,0214

water goes to where there is less water by concentration and that causes the cells to puff up with that water coming in.0219

When they a puff up, it makes that hole open up.0225

Conversely, when you pump the ions out through those membrane proteins,0229

water follows out of the cells and those guard cells kind of collapse on each other, closing that particular hole.0233

Stomata is very important, in terms of getting CO₂ into the plant,0240

and water can evaporate out in the stomata too and they can also loose oxygen from out of there.0245

But that is transpiration, more on that later.0250

But the stomata is very important for getting CO₂ into the plants.0252

Alternation of generations has to do with the lifecycle of a plant.0257

The majority of plants in kingdom plantae are mostly diploid.0264

If you remember diploid means 2 N, having two copies of every chromosome.0267

Haploid is through meiosis, you have that number and have this putting up with the chromosomes,0274

usually to make sex cells, like gametes, sperm and egg.0279

There is one generation of plant called the sporophyte generation, and that is those diploid cells.0284

Then , the gametophyte generation is the haploid.0289

This is not found in animals because you might think, do not I do alternations of generations,0293

my species were mostly diploid which is analogous to this sporophyte.0299

We do meiosis in the gonads to make sperm or egg which are haploid, and those fuse to make a new diploid organism.0304

It is not quite the same because with plants, you will have sporophyte structures all throughout the plant.0312

That then, will give rise to gametophyte that is multicellular, meaning meiosis will happen through these haploid cells.0317

Those haploid cells go through mitosis to make a multicellular gametophyte tissue, which you do not find in animals.0324

You do not find a multicellular sperm tissue, whether all together forming a tissue.0331

This is different, this is something that is unique to plants.0340

Sporophyte leading to gametophyte, back to sporophyte.0344

Depending on the plant, sporophyte can be the majority of their body0349

or sometimes even the gametophyte can be the majority of their body.0354

Plant origins, in terms of where these plants come from.0359

There is plenty of evidence that multicellular land plant share a common ancestor with green algae,0362

which is a modern day plant like protist.0368

Here are some examples of how all these green little cells are related to modern day plants,0370

that we now love.0377

Cellular cell wall, when we look at plant cell and tree, cellulose, cell walls.0379

Cellulose is a kind of polysaccharide, a large sugar molecule.0383

The cell plate during cell division, a cleavage for what happened in animal cell to split up the cytoplasm,0391

instead those vesicles lining up with cellulose allow algae to divide.0397

Similarly, it happens in land plants.0403

Chlorophyll similarities, when we actually look at the molecule that is absorbing most the sunlight,0405

in terms of making photosynthesis to happen, the actual molecular structure of chlorophyll is very similar.0410

rRna similarities, if you remember rRna is ribosomal RNA.0418

When you look at rRna which does come from DNA, in algae and plants, there is a lot in common.0424

Starch storage, in terms of how they store those glucoses that they make through photosynthesis for rainy day.0431

And then, same types of enzymes and vesicles.0438

When you look at various vesicles inside of their cells, very similar enzymes.0440

Approximately, 400 hundred million years ago, land plants began appearing on earth.0446

Resistance to drought and protection from our loss probably filled this transition.0451

Protection from water loss, protection of embryos from water loss, a very important,0456

in terms of land plants becoming successful and passing on their DNA to make more land plants throughout the eons.0463

It is something that needed to happen because if you have a very simple plant in the water,0471

a little plant like protist in the water, there is so much water in there, you do not have to worry about drying out.0479

When you are in land, sometimes you are away from water for a very long time,0484

in cases of a drought, you do not want to dry out and die.0488

Protection of embryos from water loss is important to make a new generation successful.0491

Now, we are going to get into the different divisions, the different groups of plants, within kingdom plantae.0498

The first is non-vascular plants, I know that with characteristics earlier on this lesson,0503

we said that vascularization, having these vascular bundles is a characteristic of plants.0508

There some exceptions, those other things that I mentioned these have but they do not grow tall,0514

this particular group.0519

These plants cannot pump water up very far against gravity.0521

Bryophyte is one of the most commonly known ones mosses.0526

You can sometimes see in textbooks will say division bryophyte.0531

the term division is basically like saying a plant phylum.0535

There are the mosses, I will tell you more about this on next slide, in terms of how they reproduce.0540

All that fuzzy green stuff and then this little brown extensions coming out, they have to do with the ability to reproduce.0544

There is the anthocerophytes, the hornworts, hornworts also do not grow very tall.0551

These are the reproductive structures going out there.0557

Hepaticophytes, these are the liverworts, do not grow tall at all.0560

Very unique plants, in terms of comparing them to other divisions.0565

Now, time for the bryophyte and moss lifecycle.0572

Unlike most plants, the bryophytes have a dominant gametophyte generation.0575

Most of their body is actually haploid and a small percentage is diploid.0582

You may have seen other division that is not true, when we look at ferns, cone-bearing plants,0588

and flowering plants, they are mostly sporophyte or diploid, but not here.0593

We are going to color code this, let us say that green here is going to be the gametophyte and we will say black is sporophyte.0597

Since this is might be relatively new terms for you, I am going to write next to gametophyte the single N which means haploid,0623

and next to sporophyte 2N meaning diploid.0632

You will see that gametophyte generation, there will be a fusion,0637

there will be a fertilization of haploid cells, to make the sporophyte.0640

And then, it will start all over again.0644

The sporophyte will go through meiosis to make the gametophyte and it keeps happening.0645

We look at moss, you know it is that fuzzy green stuff.0650

You will see it on rocks, you will see it in a log, it is covering a lot of your surface, honestly.0656

We zoom into that, when we zoom in, here is what we see.0662

All of this is haploid, this grow out of something called protonema.0673

I will tell you more about that in a bit.0683

I am going to draw two of these little moss extensions, part of the gametophyte generation of this bryophyte.0687

This one on the left, we are going to say that this is a female version and this is the male version.0696

You actually have two different kinds of gametes that are going to be produced.0703

You have eggs being produced in this one here and sperm being produce in this one here.0710

Deep inside of these areas you will have this.0717

If you look inside of here, here is what you are going to see, it is called the archegonium.0724

This is little cellular extensions.0740

This is like super zoomed in, and down at the bottom here, those are little eggs.0742

Here is the archegonium, I really will say archegonia because that is plural.0751

That is a nickname for female producing structure, female gamete producing structure.0758

Inside of this one, there is something a little bit different.0767

Antheridia, this term anthers is going to come up again later on this lesson.0783

Anthers are the pollen containing structures at the top of these little filaments inside of a flower.0787

This anther term comes up again and again, meaning male gamete producing structure,0794

whether it is pollen or flagellated sperm, in the case of mosses.0800

A moss actually makes flagellated sperm.0805

From out of the antheridia, you have sperm.0807

If you will to zoom in to them, they have little tails.0813

And if there is moisture, If there is dew, If there is enough fluid around, they can literally swim and end up inside of this female gametophyte structure.0817

Here is the female again, this little sperm can swim into there.0830

When you have haploid sperm meeting with haploid eggs, that is going to form diploid.0837

From out of here it is black, it is sporophyte.0844

You produce this structure, this little stock, this little capsule.0850

Inside of this capsule, all of this is going to be diploid.0854

Inside of here, you are going to get meiosis occurring to produce what are called spores.0858

This haploid spores not on the ground, and hopefully will grow into what is called protonima through mitosis.0873

Protonima are these strands of cells that give rise to new gametophyte leaf structures.0882

It starts all over again, you will get male forming, female forming, and it is just that continuous cycle happening all over and over.0893

The see interesting thing about this bryophyte mosses is, it is entirely dependent on gametophyte.0900

This bryophyte does not do photosynthesis.0904

It really does depend on this gametophyte, they are growing out for nutrients and support.0907

Without this bryophyte growing, you are not going to get this new spores being developed for meiosis,0913

to make the gametophyte generation happen all over again.0919

That is the bryophyte life cycle.0924

Now, see these vascular plants.0928

Finally, we are now into the divisions where they can grow tall, we can see trees.0930

These are vascular but they do not make seeds, we will get to the seeds later.0933

They have that water transport ability, a common way they reproduce.0938

If they do not make seeds, how do they make new plants?0943

They are the structures each one is called a sores or sori would be plural, this is a spore bearing structures.0946

Lycophyte is one of the groups of the seedless vascular plants, club mosses or ground pines.0954

If you use your imagination and you look at this picture here, they kind of look like little minnie pine trees, in a sense.0962

A lot of this in the lycophyte group are actually epiphytes.0970

They make these long whining strands that would grow around bigger trees0974

to help them get higher up and absorb more sunlight.0980

These do not make seeds but they can grow tall.0984

Then the pterophytes, the ferns or the horsetails is another type of pterophytes.0989

The division pterophytha, ferns are the most commonly known.0995

Here is a fern plant, it looks like a tree fern.0999

From out of here, you have what is called a fiddlehead.1002

A fiddlehead will actually unravel to make a new fern frond.1005

On the other side of these leaves or frond, you have the sori, those structures that do not make seeds1011

but they make spores that grow into the gametophyte generation.1019

For the pterophyte or fern life cycle.1026

Dominant generation, as we are going to see with the rest of these life cycles,1027

is going to be sporophyte or 2 N, the exception was the mosses.1031

These plants produce motile sperm.1036

It is not like pollen grains like what we are going to see with cone bearing plants or with flowers.1038

Pollen grains do not have a tail, and they are dependent on,1043

typically, wind blowing them or getting on some animal that has participated in pollination.1046

This is a zoom in of the underside of a fern frond.1052

You can see all these little orange brownish, little fuzzy things.1057

Each one of those is called a source.1061

Let us color code this again, let us say that black is going to be this sporophyte and green will be gametophyte.1064

Remember, most of the plant, most of the fern is actually sporophyte.1087

All of this, I am going to circle it in black, that is all sporophyte.1092

But inside of these little orange fuzzy, meiosis is taking place.1098

Here is how it works, if we zoom into one of these little extensions, source.1103

If we zoom into the sources, you will have what is called sporangia.1118

this thing right here, that is a part of each source is a sporangium.1136

With the sporangium, one single sporangium is kind of round structure that we have zoomed into, super zoom in,1146

you are going to have meiosis happening in here to produce what are called spores.1156

The spores fall down onto the ground, and they can go through mitosis,1168

if they are the right conditions or on moisture, they will grow into this interesting thing called a prothallus.1175

Pro meaning early or beginning, and fallus means like beginning or early shoot or twig.1189

It is interesting that they use that terminology, because from out of this which is actually a very tiny structure,1203

I drew this big, but oftentimes, you need a microscope to see this.1210

They just look like a little green dot, like this mini leaf.1214

But from out of this, you are going to get the young shoot, you are going to get a new firm going from out of this.1217

This profallus, notice I drew it in green, it is entirely haploid.1224

On one end, you can have the archegonium, that same terminology from moss, the egg producing structures here.1229

Then down here, you can have antheridia, the sperm producing structure.1242

You can have profalli, these different prothallus, prothallus is the proper term.1254

where one produces the archegonium and other produces the antheridium, but oftentimes, there are on the same one.1259

But you can have the sperm swimming to other ones, of course.1266

These structures here are called rhizoids, they are like want to be roots.1269

There is a chemotaxis that occur.1277

This term chemotaxis, it is like a chemical signal that will attract cells.1279

If you wonder, how did the sperm know where to swim to?1287

It is not like they have eyes or something.1291

Chemo taxes is a chemical attraction that is driving them towards that destination.1293

When there is enough moisture, the sperm that are produced here, they are flagellated,1298

and they will swim to the archegonium, these little flagellated guys.1304

Once they go in the archegonium and fuse with the egg then you have your new sporophyte.1311

From out of here, you can get new fern growing.1317

Of course, as this develops, this fern will grow into a full fern tree.1325

Yes, of course, the majority of the mass of a fern is sporophyte.1331

Just focusing on how the gametophyte forms here.1336

But, if we have nod find this profalli, you will not get new fern trees developing.1338

This was my little fiddlehead drawing here, showing how a new fern can develop.1344

One more thing, the prothallus fades away, it disintegrates once fertilization has been accomplished.1350

You could have at the base of a fern this a structure called a rhizome, developing.1358

The rhizome is supportive structure from which the fern grows out of it.1365

It is kind of like a structure that supports the roots, supports the shoots.1372

You can actually cut off part of the rhizome, remove it,1379

and you can have new fern structures growing from out of that part of this sporophyte tissue.1383

Ferns pretty incredible trees, a very ancient lineage of trees and it has been around since before dinosaurs.1389

Seed plants, the next two major divisions we are going to talk about,1399

they are seed bearing plants, and most vascular plant species do have seeds.1402

They definitely have their advantages, protective, otherwise.1409

Seeds are tiny sporophytes, little babies of a new plant, surrounded by a protective tissue.1412

It is kind of like a mobile room in a sense.1418

Cotyledon is a structure inside of seeds that is important to know about.1423

Cotyledons are seed structures that store food or help absorb food for the young plant.1426

With this term cotyledon, the root of that cot, ends up giving you these two.1431

These are lineages of flower bearing plants.1438

When look at division antophyta, the flower producing plants, there is the monocots and eudicots.1442

I want you to just keep in mind that, if you look at an older textbook,1450

eudicot is just called dicot but they added eu with a lot of modern terminologies.1454

Monocots, singular cot, one cotyledon in their seeds, and of course di meaning two cotyledons in their seeds.1461

The storing food part, you are going to see in the future lesson about plants.1469

the cotyledon in some plants actually will absorb what is called the endosperm,1475

the nourishing part for the little embryo is actually a part of the cotyledon.1481

Gymnosperm versus angiosperm what this has to do with is,1489

when you look at all of the seed bearing plants, gymnosperms this means naked seed.1492

Angiosperm means housed or covered seeds.1498

Gymnosperms, a classic example would be the cone producing plants.1504

Something like a pine tree, those seeds that they produce and1509

that are developing at the base of the scales of the pine cone, they are exposed to the air.1514

They are exposed to the outer environment, it is like they are naked.1519

They are not really covered or housed, and protected.1522

An angiosperm, they are fruit bearing plants.1526

The seeds end up typically inside of fruits.1529

The fruit has certain advantages, in terms of animals enjoying getting the nourishment.1532

In terms of the plant producing, that fruit structure is definitely helping to protect the seeds in the future generations of plants.1538

When you look at these seed plants, there are few divisions I want to highlight.1547

Psechidophyta, gingkophyta this one is really fascinating.1550

In this division, remember is kind of like saying a phylum which is very broad taxonomic category,1557

right below in kingdom, there is one species, the gingko biloba plant.1564

The weird thing about the gingko plant is morphologically and genetically,1569

it is so unique compared to these other modern trees that scientists are not sure where to group them.1575

It could be that they had a lot of relatives from millions of years ago but they are extinct.1581

There is just one species in division gingkophyta.1587

Coniferophyta, these are the conifers, cone bearing trees.1591

And then antophyta, these are the flower bearing plants, of course flowers here.1596

This right here, this little fuzzy like structure, it is actually a fruit.1601

You might not strike it as a fruit because it does not look appetizing.1606

But, these are seeds inside of here, this is a structure of the plants produced around the seeds as like a protective house for them.1610

Though we may not eat these, some animal may find them quite appetizing.1619

coniferophytes, the cone bearing plants, some conifer examples in the gymnosperm would be pines, cyprus, redwoods.1627

If you had a Christmas tree in the last time you celebrated Christmas, if you do celebrate Christmas, it was probably a conifer.1636

Many have needles, these very long, hard leaves covered in cutin.1643

Cutin is a hard coating around them that is protective.1650

It helps prevent water loss and will make it less likely for certain animals to want to eat those leaves.1654

That does not sound very appetizing.1662

In terms of the different kinds of conifers, some of them are evergreen which basically means always green.1664

They do not lose their leaves, they do not lose their needles, there is not a period like autumn associated with leaves falling off.1672

As long as they have enough moisture and nutrition, they will keep their leaves and retain them throughout their life.1682

Deciduous, a little bit different, deciduous trees they also exist with flowering plants.1686

They lose their leaves, typically in autumn or fall.1693

Those leaves will grow back in spring and they will retain them throughout summer.1698

gymnosperms meaning naked seed, of course, male and female cones typically exist on the same tree.1706

With most conifers, you will find these cones which of the male and these cones which are the female cones.1714

The male cones, sometimes they look kind of brownish or orange but there is different species.1726

These little cones, if you went up and felt them, a lot of them just disintegrate in your hand.1731

They are kind of sticky and dusty.1736

It is just a whole bunch of pollen grains inside of these male cones.1740

Female cones, typically larger and harder.1745

At the base of these scales, there are two ovules.1748

You can actually see them, right here and right here, two ovules that can produce eggs.1751

All it takes is a pollen grain getting into the base of the scale to fertilize the female cone,1759

and that can lead to a seed being produced.1764

In terms of economic importance, I mean with plants, in general, they are so much important,1767

in terms of supporting us and supporting life on earth.1771

But economic importance, lumber, the wood that is used to build houses, to build buildings,1774

they typically get them from conifers.1782

Lumber very important, the paper that you write on, typically taken from this kind of trees.1786

Resins, all kinds of resins used in making products, a lot of resin come from conifers.1791

You can also get resins from flower bearing plants, the anthopytes.1797

Syrup, something like maple syrup from a maple tree is quite tasty on some breakfast items.1801

for the conifer lifecycle, once again dominant sporophyte generation, mostly 2 N, mostly diploid.1811

Within the cones, you do have those haploid, the multi cellular structures that we call the gametophyte.1818

In cones male and female, they do contain the gametophyte.1824

Let us color code this, let us say once again.1828

Black is sporophyte and green is the gametophyte.1834

Here we go, when it comes to cones, they come from the sporophyte structure of a tree.1854

I am going to make this a very simple drawing, this is my quick and dirty sketch of a pine tree.1867

Gorgeous, it could have been better.1874

But here we go, there is a pine tree, on that pine tree, here is your female cone and you have your little male cones.1877

If we zoom into one of these scales, here is the super zoom in, each one of these scales has two ovules.1904

Each of those ovules, meiosis will happen within them to produce the little eggs.1929

Let us focus on one of these.1937

This is called, within the ovule, the megasporangium.1954

Conversely, with the male parts will be the microsporangium.1963

Remember, the female cone is much larger and the male cones ore tinier.1966

Mega meaning large and micro meaning small.1970

This megasporangium will go through meiosis.1972

Let us try to redraw this structure as part of the scale.1979

Here is meiosis and these are called megaspores.1986

The megaspores rise from meiosis from the megasporangium.2001

But guess what, three of those megaspores typically disintegrates, I’m going to across them out.2007

Then moving on a little bit further, let us just do the whole thing.2015

we are still retaining this structure that is black around it, but inside of it, you have your one megaspore.2026

Which we can say it is developed into something called the archegonium, that word has been used numerous times.2039

That is your haploid egg cell, I mean that is the one that is going to be fertilized by a pollen grain.2050

When we focus on the male cone, you can have this.2061

That is one of those little cones.2076

Inside of here, I am not going to draw all of them, there are all these tiny little microsporangia.2078

When we zoom into this even further, the microsporangium will undergo meiosis once again, to produce microspores.2085

Let us make note that this is, like I said here with megasporangium, this thing is called a microsporangium.2120

These individual microspores, each of these microspores is of course haploid.2136

Now, We are talking gametophyte, but they go through mitotic divisions to make a pollen grain.2153

A pollen grain ends up looking like this, if you really zoomed into it.2160

It almost looks like it has little wings on it.2164

Inside, you actually can have multiple nuclei.2166

Through these mitotic divisions, it will mature to the point that,2170

when it comes into contact with this egg that is a part of the archegonium, you have multiple nuclei.2186

One of them is called a tube nucleus, and in here is the sperm nucleus.2196

Now inside of that, this is a super zoom in, this is at the base of the ovule region,2209

you have something called the micropile.2218

The micropile is this region where you can have access to the egg when a pollen grain lands there.2220

All it takes is the wind blowing this pollen grain.2226

If it gets right here, they can actually let the sperm nucleus fuse with the egg nucleus.2229

From out of there, you can get fertilization, of course.2237

You will get your little embryo and this is actually your seed.2246

we are back into black now, sporophyte.2253

From out of there, fertilization, mitosis happens with that sporophyte to make the embryo.2255

You have this seed with oftentimes little wing on it.2262

Now, hopefully it lands somewhere where there is enough moisture, where there is enough good soil.2266

It will grow into a new pine tree or whatever conifer we are talking about here.2273

That is the conifer life cycle.2278

Antophytes, the flowering plants, antophytes include every plant that has flowers, there is a lot of them.2282

Very successful division from the plant kingdom.2288

It is the most widely distributed successful plant.2290

75%, approximately at the plant kingdom are actually angiosperms, these antophytes.2293

That is incredible, when you consider all the plants you have seen that do not have flowers,2300

there is so many more that do.2305

These angiosperms as with the conifers, you got the male and female parts.2308

But oftentimes, you have one flower that has male and female.2313

That is actually very common, there are some trees that have, this tree has the male flowers,2319

this tree has the female flowers, but most often they are together.2324

They have one home, and actually the term for that is a monoissues,2327

they have like one house for the male and female parts, as with this flower.2331

We will look at the flower parts in a moment and talk about, what is the male part and what is the female part.2336

Various life spans, in terms of how long it takes them to make a new generation.2342

With annual flowering plants, as the name says, their life is one year long.2346

With a lot of crops, the crops will last one year.2354

They make flowers, they get pollinated, make seeds which land to make new plants.2358

And in those plants that made those seeds die, one year lifespan.2364

Then the next generation does it for one year again.2369

Biannual, it takes two years, it is a 2 years span where it will take until the second year for them2373

to actually produce flowers that get pollinated.2384

And then, once that pollination happens, or even if it does not happen, their life is over.2387

And then perennials, I want to put a question mark because it means year after year, they can make flowers, they can make seeds.2392

Their life will last as long as they have enough nourishment,2403

as long as they have enough water and CO₂, and the conditions are right.2407

The temperature is right, they do not get a virus, they do not get a fungus, they do not got eaten, etc.2409

Perennials, look at the tallest trees you have seen, those are perennials.2414

They keep growing, year after year they can make flowers.2419

Alright, flower anatomy, for the female part of flower we will use purple, this is the female parts.2426

And then, let us use color green for the male.2442

Let us start with the female, ladies first.2455

I am giving you a classic version of the flowering plant.2462

When you look at flowering plants, sometimes what you are going to see here is actually very different.2466

This first structure I drew, that is oftentimes in the center of the flower, it is a pistil or carpel.2471

Some flowers can have many pistils, not just one.2476

In this case, I am just drawing one.2479

The whole thing is a pistil, and some books will actually call it carpel but pistil is most commonly used.2484

How do you remember that the pistil is the female part,2499

it is kind of silly for me to say this but this is how I remember it, when I have learned this.2504

I just picture a female spy with the gun like a pistol, and I know that that term pistol will be spelled differently.2507

instead of James Bond, maybe it is Jamie bond, and it helps me remember it.2514

The whole thing is a pistil, the top part where pollen grains hopefully will land is called the stigma.2519

I remember that, because that top part of the pistil where you want pollen to land,2526

and then start the pollinating process, it is sticky.2531

I think sticky stigma, they kind of start with that same sound.2535

The middle here is known as a style, this is the female part, ladies got style.2540

The style is that middle region, the pollen tube which you going to hear more about on the next slide, grows down in this region.2546

And then, at the bottom is the ovary which would contain ovules, the eggs are definitely down there.2554

here are the female parts, the male parts now.2564

I am going to draw 4 of them but depending on the plant, I mean,2568

if it is a monocot you would typically have multiples of 3 of these, with dicots you would see a multiples of 4 or 5.2573

I guess here I’m drawing a eudicot or dicot right now.2582

Here is the male portion, the entire thing is called a stamen.2585

The way that I remember it is, the word men, it is the male part of a flower, men is in there.2595

That whole thing is a stamen, I will just draw 4 stamens.2600

The top part, the pollen containing producing part is known as an anther.2604

And like I said before, that term antheridium, which means that is the part of the plant2609

that is producing the male gametes, there it is, the anther.2614

That part that is long and skinny is called a filament, and that is what a filament is.2620

filamentous is long and very thin.2624

Those are the male terms.2627

Beyond that, you have other structures that are not male or female, they are just supportive and they serve a purpose.2631

Those of course, I just drew petals, petal not pedal that would be a pedal like on a bike or car.2645

Petals, I drew 4, like I said if this is eudicot plant, you will typically see multiples of 4 and that includes the petals.2656

What else? There is the flower stem that leads to it growing.2665

These structures here, they kind of look like flower leaves in a sense, each one is called a sepal.2671

The sepals, those cover the flower bud, when it is not open, in a protective way.2677

Those are the sepals and those are the parts of a flower.2684

Flowering plant life cycle, like I said before, the only one of the divisions that is dominant gametophyte was the mosses.2689

We have dominant sporophyte generation, most of the flowering plant, a tree that has flowers, is going to be diploid.2697

Within the flowers, you have the gametophyte growing, male and female.2704

We got a flower, very quick drawing.2711

Within a flower, you are going to have two different sections, you have the male and the female parts.2723

Here we go, let us zoom into to the male anther.2728

Like before, black would mean sporophyte, I am just going to write sporo.2737

Green would mean gametophyte, just write gameto.2744

Within the anther, when we talk with the filament and the anther itself, it is sporophyte,2752

but meiosis happens within the anther to make a pollen.2758

If we zoom into these little units, there are these regions which inside of them, look at that, it is green inside.2763

You have meiosis happening within there to make what are called microspores.2789

Meiosis happens to make that gametophyte generation.2799

These microspores, if we zoom inside of one of them,2803

the microspore produces a pollen grain that actually ends up being multicellular.2811

That is the whole point of this alteration generation things, it is the arising of that multicellular tissue from a single haploid.2818

Here is a single pollen grain, inside of the pollen grain, there are two nuclei.2824

One of them is called a tube nucleus and one of them is called a generative.2837

Generative nucleus, it is called generative because it is going to generate multiple nuclei upon the instance of pollination.2850

This pollen grain, hopefully have access to the stigma and make fertilization happen.2858

If we focus now on what is going on in this little region, the pistil, if we zoom in to here, here is what is going on.2866

You have the ovule, inside of here you have like from that other slide, similar terminology,2887

the megaspores arising from meiosis.2917

Meiosis happens here within the ovule to make these megaspores.2928

Like I have suggested before with the conifers, typically a bunch of the megaspore, 3 of them will disintegrate.2932

The one megaspore will actually develop into this more complex structure, that is the egg that can be fertilized.2938

I am going to cross off these megaspores here.2947

If we continue this, this egg is housed within the part of the ovule.2952

You will have multiple nuclei forming.2967

You have just a bunch of mitotic divisions that happened within that one megaspore to make an egg,2971

that is really filled with numerous nuclei.2977

There is your egg cell and this forms from multiple divisions.2982

In this region here, it is called the micropile.2998

I use that term with the cone bearing plant earlier.3000

The micropile is, you need to have access of that pollen nucleus to get into that region.3004

You have one large egg cell with 8 nuclei.3012

What happens is, when this pollen grain lands here so that little male lands here,3015

you will get development of a pollen tube.3025

That pollen tube grows down the style.3028

Once again, it is like a chemotaxis, that is one of the theories of how this occurs, and depending on the plant.3033

If the wrong kind of pollen grain, let us say for another species that is not compatible,3040

lands in the stigma, it would not allow the pollen to actually develop.3043

In some plans, the pollen tube got as long as 50 cm like in corn.3049

This grows all the way down here until it gets to this region.3055

We have the egg with these nuclei, and you have a pollen tube that allowed the pollen gain access to it.3062

Remember, the pollen tube is haploid, it came from this pollen grain, this egg, haploid cells, multi nuclei.3078

And then, you get fertilization but it is actually called double fertilization.3089

What happens here is, you get N + N that is the egg cell that is meant to be fertilized.3098

The gender of that nucleus actually gives rise to two different nuclei.3109

One of them ends up being the true sperm.3113

N + N mean 2N, and you get the zygote which eventually become embryo.3118

That generative nucleus also produces another nucleus that fertilizes with polar nuclei here.3128

The term double fertilization is referring to the fact that other than this fertilization to which we expected.3135

The double fertilization also leads to N + N + N to equal 3 N, and you have a triploid endosperm.3144

This is thanks to that generative nucleus forming this sperm nucleus.3161

This nucleus that is going to fuse with other polar nuclei within this egg, to produce the 3 N endosperm.3170

Now that we have our zygote, please keep in mind that even though I wrote this in black,3179

I am not saying that these N cells are actually sporophyte.3185

I’m just making a note that this is part of the process of making that sporophyte.3189

Here is a seed that is developing from this here, here is your little embryo located here, this is all sporophyte.3194

But in addition to that, you have the structure called the endosperm which is nourishing.3205

That typically is triploid, and there is a seed code on the outside.3211

You will have that contained within a fruit, typically.3217

The fruit develops from the wall of the ovary, there is the devoiding of sugar and citric acid, and other things,3221

to develop that fruit that is going to house this seed that develops at the base of the flower.3228

There you go, that is the flowering plant lifecycle, like the previous slide with mosses, ferns, conifers,3235

we see the alteration and generations here happening.3242

Sporophyte making gametophyte, back to sporophyte, and so on.3246

But the unique thing here was definitely double fertilization,3250

that is something that is a classic important piece to angiosperm reproduction.3254

Thank you for watching www.educator.com.3260