Thursday, May 26, 2022

Botany video 3: secretory thru monocot vs. dicot stem (test 1 info)

Hey team what a day it's been it's 2 42 and uh i've already went paddle boarding with some dolphins that was nice and then i caught a flounder a large flounder so i caught my dinner yep well we're going to continue on i'm going to share my screen with you this is the second .

Video eventually i'll lose track and i won't be able to say this is the whatever number of videos so basically you're just watching these videos in order you can always go back and re-watch them today we're going to finish up plant tissues and probably move into organs but we'll see um .

We'll see how it goes this is going to be about a approximately uh approximately one hour video so we'll cover a good bit of information okay and sorry i'm moving things around a lot here now all .

Of a sudden let's see nope that's not it here we go there we go sorry about that i just wanted to show you where this powerpoint that we're working on is this is module 2 which says plants and we're in the still in the plant tissues power point .

So that's where we are at and uh just you know kind of quickly we did simple tissues last time talked about what their function was and what they looked like there's some parenchyma with very thin cell walls storage of food and water collenchyma flexible support you can see the .

Irregular thickenings of the cell walls and the collagenous or the collagen fibers that are present that gives them flexibility and then these bundles here are sclerenchyma these sort of rebars very thick lignified cell walls and we talked about sclerenchyma .

Sclerods are stone cells and we talked extensively about fibers and then we got into complex tissues we talked about xylem and we talked about phloem so um remember xylem moves the water up there's no it's not a two-way street uh phloem uh .

And there are two different kinds of xylem tracheans and vessels and then phloem is in fact a two-way street the sugar can move up or down through the sieve cells and then remember these are living cells but they're e-nuclei meaning they don't have a nucleus each of the civ cells has a cell .

Associated with it that does have a nucleus that we call the companion cell so just to remember xylem is not living at maturity but phloem is okay talk a little bit about secretory tissue uh plants make all kinds of secretory substances uh that are by secretory what we mean .

Is it's a substance that's secreted to the outside of the cell and you could compare that with animals animals have secretory tissue think about mammary glands and mammals they produce milk and they secrete it out of the cells well plants produce a whole host of different secretory compounds what .

You're seeing here is a rather notorious one because this is papaver somniferum or the opium poppy and you can see this latex this white milky latex it's oozing out uh this latex is it ends up being about 30 percent morphine and so it's a potent um uh .

Pain killer okay we'll talk a little more about that in a second let's let's make a list of different kinds of secretory substances that plants might make latex is important and it's important for a variety of reasons we use it it's .

Useful i don't know why i put a t there i didn't do very well sorry let's try this t-e-x maybe that's how i had it spelled before but it looked funny um examples rubber right so we used rubber to rubber to make tires and other things right .

Latex gloves for example condoms uh are you know made from these secretory substances of uh plants um and then um you know when you start thinking about papaver somniferum this is the opium poppy and so in this case the .

Latex is used medicinally or in some cases recreationally so a little bit of information about opioids one thing that's fascinating is that you know your brain has receptors that perfectly fit the opioid molecules and so these molecules .

Fit in these receptors and this is what accounts for the for the pain killing effect uh and also the you know the the uh the other effects of the uh the psychoactive effects of the of the opioid somniferum means to rest or restful .

So you know for a long time scientists wonder you know why in the world does your brain have some receptor that this plant molecule fits so well in and it was discovered that we actually uh it's because we make our own morphine we make this stuff .

Called endorphin so how does opium work or how do opioids work and what are some opioids well morphine heroin codeine these are all opioids and then there are lots of synthetic ones like oxycontin hydrocodone etc so endorphin is literally endogenous .

Morphine and the thing about it is is you know your body is constantly making a little bit of it at all times if endorphin is kind of known as the um you know the feel good uh one of the feel good neurotransmitters .

So when you unfortunately use opioids there's this feedback mechanism and when you when you take synthetic opioids or or even natural opioids like opium your brain immediately thinks it's producing too much endorphin and in response it shuts its own natural .

Endorphin production down this is why opioids are so incredibly addictive you cannot live without this molecule but if you abuse opioids your body stops making this molecule and at that point you have some hardcore addiction on your hands and then of course if you .

Stop taking the uh the synthetic version of the of the neurotransmitter you're going to go through terrible withdrawal situations so uh you know the take-home message there is although opioids have their place as painkillers they can be very dangerous .

Because they are such addictive and potential for abuse drugs okay it is illegal to grow opium poppies although they're commonly found in uh they can be found just in wildflower mixes that you might sprinkle in your yard .

You can also just go to the food co-op and buy uh opium or poppy seeds and those end up being uh most likely opium poppies because they're growing the opium they're growing the poppies for opium and then they're also harvesting the seeds .

Okay so what is opium it's just that latex that you saw oozing out of uh of the plant and so what the way that they harvest it is they make these little lacerations in the fruit this is the fruit of the poppy and then they'll come through and scrape this latex off two or three times a day and that would be raw opium and then .

From there you can refine it into heroin or morphine okay so there's that what are some other secretory substances oils resins these are fat soluble sticky things um some good examples uh well as far as oils go you know humans become .

Obsessed with these oils especially the aromatic ones i mean obviously we use some oils to cook but think about aromatic oils like peppermint another one is thc tetrahydrocannabinol it's a resin and you know when we start looking at these oils and resins that are produced .

By plants we immediately say would wonder why why are the plants producing these chemicals they're large compounds they're expensive to make most likely anti-herbivory what does that mean herbivore right eats plants .

So these compounds tend to be distasteful to herbivores to things that might come and eat them like insects or even mammals like deer right so you know peppermint oil is a good example also the the glands around the female flowers .

Of cannabis produce thc right and it's believed that this sticky resin is uh there to prevent herbivory of the of the seeds ultimately okay now humans are obsessed with these go to the go to earth fare and look at all the essential oils there's probably 75 different ones right where we extract .

These oils and we use them because they smell good to us of course thc you know it's psychoactive chemicals so it's used as a drug it's the active ingredient in cannabis okay and there's also cbd which is another type of resin that's .

Produced or oil so that gives you kind of an idea you know these latex and oils and resins they can be used in industry they can be used uh you know to make tea or peppermint tea or they can be used as recreational drugs in the case of thc .

Or medicinal drugs as in the case of thc and opium latex so that's pretty good for secretory substances for plants okay moving right along now we want to talk about meristematic tissue .

And it's a kind of a funny word there are lots of funny words in botany and i don't know for some reason mary stem the word mary stem seems kind of silly what is meristematic tissue mary synthetic tissues are regions of actively dividing cells and plants and so you start thinking about how plants grow .

Plants grow from the tips of of the plant not from where the plant comes up out of the ground right and so what you're looking at here is this the tip of a coleus plant and you can see this is a leaf and these are very small leaves here and this is another leaf and these mounds that you see here .

Are the buds and inside of the bud is what's called an apical meristem and this is a region of actively dividing cells remember what that process is right how do we make more cells asexually what's the process mitosis right so this is a region of mitosis and .

Then here are some lateral buds a little lower down which are also mary stems so we have different kinds of merry stems the apical stem apical meristem increases length of the stem so as these cells do mitosis and divide .

The stem grows in this direction okay so that's an example same thing in the root in the root we have and when we talk about uh organs we'll talk more about roots this is the root apical meristem same thing it increases the length of the root .

Okay so we have increase in length sams and rams sam is shoot apical merry stem and ram is root apical meristem but then it gets pretty complicated in a woody stem right because we have uh didn't mean to hit that button there we go .

Uh because we have these different regions of tissue and there are tissues that form a cylinder and this is the one uh what have i done i've lost my what's my ability to write that's unfortunate i don't know why that is let's see what's happened here i thought i took a screenshot of it but .

Maybe not there we go okay so the important word in this image for now we're going to come back to this but the important word is vascular cambium okay anytime you see the word cambium cambium is a merry stem but it increases girth so it's laying cells down in this .

Direction okay and in doing so it makes the stem bigger in this case we're looking at what we would presume would be like the trunk of a tree right and so here's the thing the vascular cambium makes more more uh vascular tissue if you recall the vascular tissue .

Is the xylem and the phloem and so um here's the xylem in here the wood and then it turns out that the phloem is right in this region and i'm going to actually draw this so that we can see a little bit better what's going on let's do that okay so let's say we have a tree and .

As you may know you can count the rings of xylem and know kind of how old the tree is right then we have this region right here but i'll do a different color and i'm going to label all this stuff here in a second don't worry and then we have this region right here .

It's a little hard to draw so you get the idea and then we have all these different colors it's kind of crazy because we have all these different layers and we're going to revisit this when we do organs this is obviously the cross section through a stem a woody stem .

And then we'll go back to black and here's the okay so no time like the present to learn the different layers of tissue here because we're talking about these cambial layers and i'm going to lay i'm going to label those this is the vascular cambium .

And each year during the growing season whenever that is it makes more xylem and phloem is the vascular tissue right okay and there's a rule about how it lays this xylem and flowing down and the rule is it always makes the xylem to the inside and the phloem .

to the outside and so what that means is each year that of growth there will be another layer of xylem laid down to the inside of this vascular cambium and another layer of phloem lay down to the outside so xylem inside .

And flow on outside but we have another cambio layer here and it's this one right here and this one is called the cork cambium and the cork cambium makes more cork each year what's cork well you think of it as the bark right so this is the cork right here .

Okay so digest all that for a second think about these different layers what is all this tissue well uh in black on the inside this is the xylem and then blue must be the phloem because it's on the outside of the vascular cambium and then the court cambium it makes the court any time you see this word cambium .

Anytime you see this word think it's a merry stem that increases girth and now think about this this is a cross section but the vascular cambium literally forms a cylinder that goes all the way up the trunk of a tree right goes into every branch and every stem and even into the leaves .

And these are regions that can do mitosis and make new cells okay lots of cool stuff here and now we can you know we can look at this image again and see uh we'll talk when we do stems and we'll talk about heartwood and sapling and all that okay .

All right y'all that's good we're moving along and just note that that is the last slide in this particular power plant so what we're going to do now is we're going to move into the next power point which is a plant organs power point so let's look at that .

And you can see there is some required reading for you uh you can read uh plant cells and if you haven't already replant tissues and then here's the plant organs powerpoint uh and uh there's some required reading about plant organs now when you start thinking about plants you realize well .

Um plants aren't as complicated as animals think of all the organs in an animal right i mean you got your heart your lungs and your liver and your skin right plants are pretty straight forward we have roots we have we can break plants up into .

Vegetative and reproductive organs and we have for for vegetative organs we have roots shoots or stems and leaves roots shoots and leaves and then for for reproductive organs we have flowers and fruits and so really there are just five which is kind of nice .

Not a huge amount to know when we do all of these we want to know primary function and secondary function that's important okay so let me just do a screen sketch of this and we can think okay what about roots what's the primary function and then we'll talk about secondary .

Functions functions anchor oops anchor to substrate and you know usually the substrate is the it's the earth right it's dirt but it could be a rock or maybe it's who knows what it's rooted on bedrock okay what else that's a primary function of .

Roots the other very important primary function of roots is absorption what do plants absorb water and nutrients so the roots are very well adapted to absorbing water and nutrients directly from the earth from the soil or if it's a water plant they can absorb .

Them straight from the water right and then it also anchors the plant and supports it okay so we have that now if we start thinking about roots uh and how they grow if you think about a big oak tree let's say one thing you might think about is you know how far do the roots go .

Under the ground let's say the canopy you know goes out here a few leaves on my oak tree you get the idea how far do you suppose the roots go and how deep you might be surprised to know that most trees in most trees the roots don't go very deep into the ground .

Usually about the first three feet of the earth is where you'll find the roots there are obviously exceptions some plants are strongly tap-rooted and they might have a root that goes much deeper how about how far do they creep out well it turns out they go further than the canopy .

Usually one and a half times canopy in this direction so you can bet if there's a big oak tree in your yard and that those roots are going all up underneath your house okay makes sense i hope so there are two basic types of root systems we can we can think of it that .

Way and one is called a fibrous root system and so what you're looking at here is a coleus plant and in the coleus uh or in a fiber root fibrous root system all of there are many roots and they're all roughly the same there's not big ones .

And little ones per se they're all roughly equal one to the next okay compare that to a tap root system you're all familiar with the tap root system because of a carrot is a really good example and so in a temporary system you have this one central root .

And then branching off of this central root are lots of smaller roots which we often call rootlets okay and they don't always have to have this exact form uh for example uh in the case of a carrot uh depending on the type of soil that .

You grow it in and clearly they grew this just for the for to show this these rootlets here but one of the things is if the root hits a rock or something like that it will often branch and so uh you could have branched carrot roots but for the most part it has a taproot things like carrots and parsnips .

Beets okay now we want to do at this point is we want to look at roots we want to look at them in cross section and then also in longitudinal sections so we want to think about now we have to think about tissues we're looking at .

This thing uh anatomically right and so let's think about these different the different tissue types we've already talked about right we talked about parenchyma xylem and phloem and we're gonna see actually all of these different tissue types in here so we start at the outside .

And like just imagine this is a carrot it looks kind of like a carrot cutting cross section epidermis all plants are covered all the surfaces of all plant parts are covered with an epidermis or a skin what do these cells look like they look like those very thin walled cells .

And in fact this is all parenchyma so think about when you eat a carrot you know this sweet part of the carrot is this part here and it's parenchyma storing water and sugar some starch okay now we have several layers in here that are difficult to see i'm going to .

Draw them in i'm going to draw a layer here it's a single layer of cells and i'm going to draw let me do a different color let's do let's do this color what the heck i'm going to draw this okay and then i just want to point out .

We have this in the middle and then we also have these little bunches of cells on the corners of this sort of star like this there are a bunch of cells in there okay so that's actually kind of nice we can see all these different tissues if we draw them in so here's what they .

Are this one is called the endodermis this one is called the pericycle strange names i know perry cycle is a strange name the pericycle it turns out is a cambium what does that tell you a cambium is a .

Is a merry stem that increases skirt this is what lays down new uh vascular cambium okay and we're going to get to that the endodermis is like the security system for stuff that gets absorbed by the plant .

And is trying to get into the vascular tissue in here and so we're going to talk about how the endodermis kind of scrutinizes and we'll we'll talk a little more about that in a second it scrutinizes what can get into the vascular tissue because think about it if it gets in the vascular tissue then .

It has access to the entire plant right if it gets in the phloem it can go up or down so what's this this is phloem and this is xylem and keeping with our you know what we talked about before phloem is to the outside xylem is to the inside okay .

So there's all those different layers and the one that we need to talk a little bit more about ends up being the the endodermis okay so let's just take a second to do that i hope you all are enjoying this lecture i know it's these are difficult times for everyone and .

I hope you're all well i'm a little bit tired i had a big day between the flounder catching and the paddle boarding with the dolphins the one good thing about teaching online is i can be wherever i want so that's been kind of a blessing but i do miss my students i'm just seeing your pretty faces all the time .

Like i used to get to do okay so endodermis it's really made up of a series of cells let's see so let me just let me just draw out the xylem and the phloem just so you know where we're at there's the xylem .

And then we have this phloem i'm not going to put the pericycle in there there's this and then we have this little it's a single layer of cells which is very strange and i'm going to draw these i'm going to take a second to kind of draw these i'm getting better with this drawing stuff on this board .

Here i have to say getting pretty coordinated maybe i spoke too soon uh okay so this is the endodermis okay let's to the inside xylem into the outside phloem this is the endodermis if you look at one of these cells you'd see it's three-dimensional it's a box like this .

Right it's very much of a box of a cell and here's the crazy thing y'all the side walls like this sidewall and this side wall and the top and the bottom are all covered with a waxy substance which is called subaru .

Okay it's very thick there's a side and a side of the top and the bottom okay and so the only walls that aren't cover the front face right here and then the back face back here and i know it's three-dimensional it's a little harder to see but if you can visualize it what this means is that anything that's .

Passing from the parenchyma out here through the endodermis and gaining access to the vascular tissue literally has to pass through the front of the cell and out the back okay and so what then happens is these cells actually are able to scrutinize and so here comes stuff .

And it's going through like this okay it's the bottom and this is the top and there's one side and one side so what this cell can do is it can scrutinize what gets into the to the vascular tissue so it might not allow certain things to go in .

Uh it's pretty good at filtering out things like bacteria uh and large particulate matter and so because of that you can usually you can say you can safely drink fluid out of a out of a plant and it's relatively pure wouldn't you wouldn't .

Expect it to have any sort of bacterial contamination okay so you can think of the endodermis as the security system of the of the root and keeping stuff from getting into the plan okay okay let's see what now now we can talk about secondary oh no actually i'm .

Sorry we have to think about a longitudinal section of a root now it's a lot of morphology here but since we're not really getting to have lab with microscopes this is good so we have these different now think about your finger you know before we were looking at it if you cut your .

Finger crossways now think about if you cut your finger long ways like this is a longitudinal section there's the tip of the root and it's a lot in the long section uh and in this case we have these different zones .

We have at the tip of the root the root cap and we have the zone of cell division well you know what this is mitosis right this is where more cells are being made this is basically the ram the root apical meristem that we talked about before .

Right in this region and then these are cells that are the products of this mitotic division and this is where they get longer so the cells literally start to elongate and then even further up is the zone of cell differentiation and so this is where you get .

Things like xylem and phloem but you get differentiation means that these cells begin to differentiate into the kind of cell they're going to be when they grow up like a xylem cell or a phloem cell or a parenchyma cell okay so anytime you make a longitudinal section of a root you can always see .

These different zones that are present you can't necessarily tell where one stops and one starts i will tell you that but it would be good to know them in order maybe i'll say name the four zones in order from the root cap up you know something like that now the root cap is especially interesting .

It is responsible for the gravotropic response of roots and what we mean by that is there are special cells in this root cap that can detect gravity and it's it's remarkably similar to the way that .

To the cells that are in your inner ear that can also detect gravity if you look at these cells they're boxy cells like this and they have little hairs at the bottom and floating around inside the cell are starch grains this is starch and so the way the root knows what's up and what's down .

Is if the starch grains are stimulating the hairs then it knows that it's upside down okay so roots will always grow downward it doesn't matter how they come out of a seed they always grow down because they have a scraptropic response okay the zone of cell differentiation is is also important because it's the root .

Hair zone and a rude hair or is an extension of the epidermis of the root so it's really cool to see under the microscope a lot of times the nucleus will mosey on out into this hair the nucleus of the epidermis cell so a root here is literally one cell it's .

An epidermal cell with this extension on it what's the point well increased surface area right and we see this in um we see this over and over in science uh if you want to increase surface area just project something outward and so we'll say a couple of words or a .

Few words about about roots and their ability to absorb they've done studies a lot of the studies are done with rye plants um rye is in the grass and so let's say you got this grass plant .

I don't know why it's not green it should be that's okay and you got all these roots and off all the roots you got all the root hairs right you get the idea well um how many roots can one rye grass plant produce 40 billion roots .

Holy moly how many root hairs 60 trillion and then you start thinking okay well what's the surface area of all that the iron it's all three-dimensional right everything's look at your finger it's three-dimensional it's like your finger if you ironed it all out it would have .

The surface area of a football field and so that gives you the idea of the incredible capabilities of absorption for uh for roots okay all right we're doing good we're going to keep going okay now we think about secondary functions well there are lots of secondary .

Functions and roots uh one of the really important is uh property but there are other for example a cornfield gets blown over in a big thunderstorm something like that and you think oh poor farmer all his corn is laying down but within a matter .

Of days it will literally prop itself back up right and that's because of these roots that are gravitropic and detecting that it's sideways and then it pushes itself back up storage roots are obviously very important it is .

Important to note that yams and sweet potatoes are in fact good examples of storage roots but that what about an irish potato is that a root no irish pears are actually stems not roots okay but yams in fact .

Are roots what are some other ones beets carrots lots of other ones right turnips these are all storage roots think about this in this case the brand just this is a strangler fig that you see here and this is a really dramatic example of aerial roots .

They call it a strangler fig because typically what happens is this tree will start to grow a seed will germinate usually they're spread by birds and it might germinate in the crown of a of a palm tree they're tropical trees so imagine a big palm and this little tree might start to grow .

Right here in the canyon and it will grab into a strangler fig and then as its branches come down it will literally it will literally strangle this tree like this and so you know maybe somewhere right in here is where the palm tree was and now there's a hole in .

Here where the palm trees died and filled this space is really dramatic okay uh aerial roots are sometimes called adventitious roots you can also see them on poison ivy which is cool let's look at that real quick this is interesting oops yeah here we go this is a great .

Image of uh ariel roots or adventitious roots oops sorry let's look at this one see all these masses of roots this is not a it's not a parasite it's not taking anything from the tree it's just using these roots to grow .

Up the tree okay good to know and then the metaphors is the is the the last one that we'll look at um sorry i'm just checking the time okay we're good uh pneumatophores you see these typically in swamps areas where plants are growing in water and pneumato air right .

And what these do it's believed is provide gas exchange for the roots because the roots are growing in water there's very little oxygen and so they need to have a way of getting oxygen so o2 is going in and co2 is coming out and so it's a way to do gas exchange because the roots are living cells and .

They have to be um you know they have to uh have a way to get oxygen and have to have a way to get rid of co2 so we see these in in swampy areas mangrove is a really good example and that's what you're looking at here there's the kind of a plant okay good .

And i think that's probably the last slide for roots that brings us to stems and we might as well go a little bit further see if we can get through stems what do stems do well pretty straightforward there are secondary functions of stems but .

Primary function of stems is support the leaves which are the photosynthetic part of the plant and transport right they transport water up to the leaves they transport sugar up and down .

and they also support the photosynthetic organ or the leaf and now we have to take a little time out because we need to do some uh we need to do kind of a little sidebar a little diversion for just a second and .

That this will actually be the last slide that we'll look at because we're going to do a little chalk and talk here for a second there are ways that you can kind of categorize or classify plants okay and we're going to look at some different .

Ways to group plants okay and one of the ways to group them is whether or not they are woody or herbaceous these are kind of two general ways you could take any vascular plant you can say it's either woody or it's herbaceous that's one way to to lump them together .

Woody plants by definition have some kind of persistent above ground vegetation trees and shrubs right there's always something above the ground that's alive think about trees i mean in the winter some of the trees here lose their leaves .

But they're still above ground portion that's alive same with shrubs herbaceous no persistent da da da right above ground vegetation okay uh can you think of an example of an herbaceous plant sure of course lots of examples we'll get to that .

Another way to group plants is whether is by their life cycle are they an annual or are they biennial or are they perennial i think there's two ends in that but i'm going to leave it like that let's stick another one in there there we go perennial .

Oh gosh i'm sorry i don't think there is okay what does this mean how it has to do with how long it takes for the plant to grow and complete its life cycle annual plants live one year they start from a seed they grow vegetatively they flower they .

Fruit they make a crop of seeds and they die all within one year of time okay biennials by means two these take two years to complete their life cycle and then in a perennial i think there's two r's it's either two r's or two ends we'll look it up in a second .

These have indeterminate lifespans they just grow year after year right and they just keep coming back okay so you know here's the thing now we can put these two words together and we can say oh it's a woody perennial or it's an herbaceous annual or an herbaceous biennial okay .

A good example of an annual corn doesn't matter where you plant it in the world it grows it flowers it fruits all within a year good example of a biennial carrot carrots we grow as an annual crop but if you leave them in the ground the spring there's the carrot the spring of the .

Second year it will send up a flower and then it will die and that's the end of the carrot okay so they live two years perennial uh how about an oak tree you know year after year after year so let me ask you this can you have an herbaceous perennial does that make any sense .

It does it does make sense herbaceous perennial herbaceous no persistent above-ground vegetation but perennial meaning it lives an indeterminate lifespan example of an herbaceous perennial dandelion think about it the dandelion comes back every year in your yard in .

The same spot it survives the winter with its perennial taproot right so you can have an herbaceous perennial can you have a woody annual that doesn't really make any sense right because if it's woody it has persistent above ground vegetation year after year .

But if it's an annual it only lives a year so that doesn't really make any sense okay there's a third grouping monocot versus dicot the word monocot and dicot from come from these little structures called the cotyledons and .

If you see a diet think about when you plant beans in the ground they come up out of the ground they have two little cotyledons these are the seed leaves okay monocot means one mono has just one okay so uh beans or dicots corn is a monocot you could .

Count the cotyledons and that will tell you if it's monocot or dicot but that's not always going to be practical i mean who's going to just happen to be there when the little seedling is germinating right there are other ways look at the leaf structure specifically the veins .

And in a monocot the veins are almost always parallel to one another in the leaf like this there must always run in a parallel fashion okay in a dicot the leaves there's a bean leaf and they have a what we call a reticulate .

Vaynation meaning the veins branch there's often a central vein and then those veins branch and branch further still we call that reticulate i think like a reticulum is like a spider web okay you can almost always you can be walking around outside you know look at a leaf and tell if it's .

A monocot or dicot almost always 99 of the time it will be accurate just by looking at the way the veins are in the leaf it's a really good way to tell one other way flower parts like for example petals in monocots they're almost always in threes .

And in dicots they're almost always in fours or fives this one doesn't always work but if you combine it with the leaf vein thing you can 99.5 percent of the time telling monocot from the dicot what i mean is maybe it has three petals or six .

Petals or nine petals or maybe it has if it did it would be a monocot or maybe it has um four petals or eight petals or five petals or ten petals or some multiple of these okay so there's all that and let's see where we're at with the time .

Yeah i think we're um i think we're kind of to the end of the uh to the end of what i wanted to cover today in this powerpoint uh and we'll come back to the monocot versus dicot stem slide next time and see how there is in fact a fourth way to tell a monocot from a dicot if you're walking .

Through the woods and you happen to have your handy dandy microscope you can make a cross-section of a stem and look at the vascular bundles is what we're looking at here so we'll come back to this slide next time okay and it's been fun teaching you all so far i hope you're learning and enjoying .

Feel free to watch the video over and over i'm sure you're all gonna do that otherwise uh i will see you next time take care sayonara adios bye bye

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