Vascular Tissue

by Jason Amores Sumpter
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hi. In these videos will be looking at the various tissues found in plants, tissues. You might recall our special collections of cells that usually air from a similar origin and have similar function and basically unite to carry out some specialized function of an organ. Now the first type of tissue in plants. We're gonna look at his vascular tissue, and we've actually talked about vascular tissue before when we talked about general plant biology. Now, vascular tissue transports water nutrients and the photosynthetic products around the plants. And sometimes these could be massive distances. I mean, think about a redwood tree, Those huge giants. Those plants have to carry water up from their roots in the ground, hundreds of feet in the air. I mean, it's mind boggling. Thebes distances that some plants have to transport various materials. Now, vascular tissue is grouped into what are called vascular bundles. You probably actually seen these before. For example, in a stock of celery. When you cut it, you can actually see the vascular bundles there, these little dots that you can see in the plant and these vascular bundles actually run the length of the stem, um, vascular tissue is usually broken into xylem and flowing. Xylem is the water conducting tissue. Uh, it brings water and dissolved nutrients up from the roots to the chutes. So this is uni directional. It's bringing this stuff up and on Lee up. It does not float. Bring water down, for example. There wouldn't really be appointing that, though, If you think about it. Waters absorbed in the roots It's needed up in the chutes and other parts of the plant, so the asylum on Lee has toe worry about bringing it up. Now xylem will be composed of what are called track kids and these air long thin water conducting cells that are found in all vascular plants. And they have what are called pits. Pits are openings in the secondary cell wall that allow water flow. Andi, there's Onley primary cell wall present in these pits. So in our diagram, let me actually jump out of the way here. You can see we have some pits labeled in our tray kids, and you can see them right here. There's another one right here, and these allow for water flow again. And in those pits there is no secondary cell wall right. None of that Onley primary cell wall at the pits? No. Some plants have vessel elements. Angiosperms specifically have vessel elements. Some other plants do too. But mainly they're found in angiosperms. And these compared to Trey, kids are much shorter and wider. Um, and they also have pits, but they have these special openings as well called perforations. So trade kids air kind of like long thin tubes. Vessel elements are shorter and wider. So think of it as a, uh, a tray kid as a thin pipe and vessel element as a very wide pipe. And these vessel elements have what are called perforations, and they're basically just openings in the cell wall that you can see here that allow for water conduction. And actually, because of thes perforations and the morphology, the shape of the vessel elements, vessel elements are actually better able to conduct water than Trey kids. Or I should say they're able to mawr efficiently conduct water than Trey. Kids now xylem also contain what are called fibers, and we're gonna learn more about this later, which are certain type of cell called a scaler, and came a cell. We're gonna learn more about these later to they also contain Parent came a sells for lateral transport of water. Right xylem are Their main job is to get water to flow up. It's gonna be different cells that transport water laterally around asylum. And we're gonna learn more about these two types of cells later on. Uh, and don't worry, we're gonna bring it all back together. So moving on, let's take a look at flow. Um, these air the other main type of vascular tissue and flow them conduct sugars, amino acids as well as chemical signaling molecules like hormones. And they are bi directional, right? They can, um they can conduct these things between the roots and shoots. They could go up and down flow more made up of what are called SIV tube elements. These are specialized. Parent came A cells that transport sugar and other elements, and they have what are called SIV plates. If we look at our sieve tube element here, which is going to be this cell, you can see the sieve plate at the bottom has a bunch of holes in it right that allow for the transport of various materials between cells. You also have called companion cells, and these support the sieve tube elements both metabolically and physically. Um, the sieve tube elements lack, for example, mitochondria. So these companion cells, they're going to keep them alive so they can keep doing their job. They the companions cells also helped produce membrane for the city of tube elements. So thes sieve tube elements really rely on these companion cells in order to carry out their function that let's turn the page.