I did notice that um there are a few students in the comment section asking about flm structure and function and to be fair a lot of students who I do teach in face-to-face classes also request that I go into detail about the FL structure and function because it's quite confusing actually isn't it so we will start by describing what exactly is the flm so the flum tissue is categorized as vascular tissues and why do we call them vascular tissues because they contain tube like structures but the tube like structures in the flum actually transport sucrose and amino acids these are the two main things that flum transports inside the plot where are the location of the flo tissues as you can see here I'm showing you the root uh cross-section and the stem cross-section or the and the leaf cross-section uh TS just means transfer section which means a crosssection same thing where I have highlighted in orange or brown or beige I have no idea what that color is looks beige-ish okay um that's where the flum tissues are actually located so you have to be mindful as to the location of the flm in The Roots the stem and also the leaf at least that's the first thing we have to know so the thing we have to talk about then is what is the flm the flm while it is described as a tissue it is not just a single thing but it's actually made out of two different types of cells and the two different types of cells are the companion cells and the flam SE tube element some books will just refer to it as the SE tube element but both are accepted in the exam so let's talk a little bit about the formation of the flum again good news you don't have to memorize this but it's good to understand where the flum comes from so remember the flum is made out of uh two different types of cells and the black color cell is a companion cell and the orange color cell is the um immature or the young flum sea tube element and notice that the companion cell and the flo SE tube element they are connected by something known as the plasmo Desma in the middle that's the cytoplasmic connection that they have between the two so what I'm doing here is I'm going to show you a few companion cells and a few flam SE tube element and what actually happens is notice what happens to the orange color cells those orange color cells the cell walls will start to break down all right uh that's normal stuff but it doesn't break down completely like the xylem vessels there are still like some cell walls that remain in place so and then some of the cytoplasm and the organel will also start to drain away within the sea tube element and that's how the flam sea tube is is actually formed the flo sea tube is made out of many sea tube element cells joined together and that's the tube the orange color section over there that I'm circling is actually the seeve tube where Transportation takes place but the flm itself is actually made out of two things the flum is made out of companion cells connected to the flm SE tube element through the plasmo Desma that is something very important that we have to know so when I'm just zooming into one of the companion cells and uh the flo SE tube element we notice that the companion cell still has important organel like it has the nuclei it has vacu it may also have organel like mitochondria rough ER GG apparatus and such but look at the flo SE tube element it does have a little bit of cytoplasm that uh as as I'm just showing you through the arrow but the volume of cytoplasm is almost very negligible it is important to have some cytoplasm obviously uh for the flo SE tube element I'll explain why but the point of the matter is the flo SE tube element will not have a lot of cytoplasm and uh some students will ask does it have any organel like mitochondria it may have like a few mitochondria but it it usually does not have nuclei and other large organel another very important thing to know about the flo SE tube element is the parts where I'm highlighting where the cell walls are broken down into those tiny pieces and those are referred to as SE plates and again I'm just circling over there the companion cell and the flo SE tube element are connected via the plasmo Desma so if you still can't imagine this uh let's try to draw this out in a slightly different diagram remember we are looking at this through a longitude udal section now if I were to highlight that yellow strip over there and look at it through the transverse section transverse meaning to say we look at it from the top what we will see is the companion cell with the vacuum and we will also see the SE tube element where the um they are connected to the plasmodesma and the SE tube actually has some cytoplasm in there but if I were to highlight that particular section and if I were to view the FL through the cross-section in this area how it will look like is it will actually the the the it will the companion cells still look normal because I can see the nucleus but where I'm highlighting they are not connected through the plasmodesma so how it will look like is you will actually be able to see two different cells how does the sea plate actually look like the sea plate looks like a cheese grater doesn't it and and the Sea plate just has those tiny little holes to allow transportation to happen that's what the sea plate actually looks like by the way um so the sea plate is just the broken pieces of cell wall it's not totally broken there are some tiny little holes that forms the SE plate if you still can't imagine this let me try another method I'm going to do a three-dimensional view of the drawing so I'm drawing out the companion cell in black and the orange color cells as you can see there quite elongated I'm going to make it a bit more three-dimensional those are the flam SE tube element all right so I'm drawing out two flam SE tube element and those um and you can see the companion cells it has um cytoplasm they are connected to the SE tube element via the plasmodesmata and uh and the flo SE tube element has a little bit of cytoplasm not a lot but it has a little bit okay and what is very important to know those highlighted parts are the SE plates so this is just a threedimensional dional diagram of how the flo sea tube looks like it's not the best diagram I've drawn but it kind of gives us an idea of what the flum is all about so long story short the flm tissue is made out of two types of cells companion cell and the flo SE tube element and the companion cells and the FL SE tube elements are joined together through the plasmodesma that's the first thing we have to describe when we are talking about the structure of the flm