Epidermal and Ground Tissue

by Jason Amores Sumpter
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epidermal tissue is kind of like the skin of the plant. It protects the plant from pathogens physical damage and also helps prevent water loss. Now epidermal cells will actually secrete this waxy film called the cuticle that helps prevent with helps prevent water loss. And you can see the in this image the water beating up on the surface of this plant because of the cuticle its hydrophobic and causes the water to beat up on the surface. It also prevents the water from leaving the inside of the plant. Now, sometimes on the epidermis of plants will find what it called. Try combs that air little hair like structures made of specialized epidermal cells. And they carry out a very wide range of functions. Um, they can be involved in water loss. They can help defend against herbivores by containing some sort of nasty chemicals like these air chemical. Try a combs here that are meant to prevent herbivores from eating the plant they cover. Uh, they can also help reflect sunlight, and in fact, they can even be involved in eating animals like we see here. This stock of the plant is covered in these. Try combs which are the little hair like things with the beads on the end. And you can see that these try combs have wrapped around this hapless insect here, which is now destined to become plant food. Ground tissue is the third type of tissue found in plants, so we have epidermal tissue, vascular tissue and ground tissue. And ground tissue is basically everything that is an epidermis or vascular tissue. So it's kind of the grab bag, but generally speaking ground tissues gonna be responsible for producing and storing important molecules for the plant. Generally, we can separate the ground tissue into two regions the pith and the cortex. The pith is going to be this inner region here, and it is basically ground tissue that's surrounded by the vascular bundles. Now what we're looking at, just to be crystal clear is the cross section of a plant stem right here. So basically, if we had a plant stem and I don't know, like, here's a little leaf coming off of it, you know, if we cut that across and then took that piece and were to look at it, look down on that cross section. That's what we're looking at right here. It's that interior layers, the pith. You're gonna find the cortex, actually, all the way out here, the layer marked six. This kind of dark layer on the outside. That's the cortex. It's the ground tissue outside of the vascular bundles. So this whole region in here, those air, the vascular bundles this region marked three is the asylum spelling it the French way there for the next 30 on the end. Kidding. And then four Here, this is the flow him and these are the vascular bundles. So the pith is the inside six. That's the cortex on the outside. And seven, What's labeled seven here is actually our epidermis, so the cortex can actually be broken down into, uh, certain layers itself. We have the Endo Durmus, which is the innermost layer of the cortex. So it's going thio form the cell boundary between theme the, um, the cortex and the vascular tissue of the plant. On the other side, we have the Paris cycle, which is a thin layer of tissue between the Endo Durmus and the flow. Um, so essentially, the if we were toe kind of zoom in on this image right here, we'd basically have the flow, Um, which is layer four. And then we'd have the Paris cycle, and then we'd have. Which is you can't really see here. It's not later. Five. Layer five something else, But you don't need to worry about it. So basically, just to make this crystal clear, let me jump out of the image and write this in. You have the flow him, the Harris cycle and then the Endo Durmus. And we're going deeper into the plant in this as we go along this way. All right, let's flip the page and talk about some of the specialized cells of the ground tissue system.