Phenotypic Plasticity

by Jason Amores Sumpter
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plants have an amazing range of FINA typical plasticity, meaning that they're able to take these basic structures the roots stems and leaves and modify them to gain a significant variety of functions. Now, I don't really want you to memorize any of this. I'm more just want you to get a qualitative sense of the breath of morphological variety that plants can take on. So let's start with roots now. We talked about Advantis cious roots before, which are those routes that are gonna come from a stem. And there is a special type called a prop route, which is basically a an advantage cious route that props up the plant. It gives it aerial support. So these air modified roots that give the plant ah little boost above the ground. Right here we have a picture of a corn plant which has thes prop roots. But, uh, these prop roots air also seen in, for example, mangrove trees, which live in like a brackish water and use the prop roots to kind of prop themselves out of the water. Go figure Now, new metaphors are generally advantages that they don't have to be, and these are special, modified routes that allow for gas exchange. You can see them in this image. All these little, uh they look like sticks popping up from the ground. Those air, actually roots. Technically there, Newman. Ah, fors. So those air routes that air doing gas exchange plants again like mangroves have these because, uh, for example, with the mangroves they live in that brackish water. They still need thio extract gas. So these new metaphors allow them to pull gas out of the air by sticking up above the water. Uh, now let's move on and take a look. A tsum modified stems. So, for example, we have cat die, right? A cactus is basically a stem, but it's been modified for water storage. Right? You know, it's the old myth. If you're stuck in the desert, find a cactus and drink it. I don't recommend doing that. Drinking from a lot of cactuses Will, actually CAC ty Rather will make you very sick Or maybe even a little more than that. See some crazy things. Let's put it that way. Now. Stolen zones are a type of modified stem that allow a plant to produce a new individual above ground can see an example of a stolen right here. This is the stolen. It's being shot out of the plant and it where it lands. It produces a new individuals. Sort of the opposite of a stolen is a rhizome. Um, and this is basically the same type of thing a stem projection that comes out this time It goes underground instead of going out above ground and where it lands, it produces a new individual. Now, stems can also be modified into what are called stem tubers, most notably things like potatoes. Yeah, potatoes. Air actually just modified stems modified to store carbohydrates. And, uh, another structure you probably didn't realize was actually a modified stem is a thorn. Thorns are just stems that have been modified into these defensive structures. Let's lastly, take a look at some modified leaves. Bet you didn't realize that an onion is actually a modified leaf. Yes, the layers of an onion are all modified leaves. Uh, it's called a bulb, and it's basically leaf that's been modified for food storage. So just like a stem can be modified for food storage right with the tubers. Leaves can also be modified for food storage and don't forget. Earlier, we looked at the example of a carrot, which is a route that has been in some cases, in some sense, modified for food storage. Now, succulents are not only drought friendly plants, and hopefully, if you live in a drought stricken area, you'll replace your lawn with some nice succulents. But succulents have a modified leaves that improve water storage there very often compared, uh to capt I Because of those similarities, you know, they have the same kind of, uh, almost like feel to them. And a nice example of a succulent is, uh, the gave plant, which is what tequila comes from. Also, Moscow don't discount mescal. Very underrated. Now, tendrils are another type of modified. Leave these air how climbing plants like vines are able to grip onto surfaces so they have these modified leaves that almost act like a like grappling hooks, right. They wrap on a surface and grip it and allow the plant to climb vertically. There's also leaves that act as floor floral mimics, basically like pretending to be a flower. Uh, perfect example of this is poinsettia, which has thes leaves that turn red to mimic the appearance of a flower, even though it's actually just a leaf. And this is done to help with insect pollination. There's also traps like the Venus flytrap, right? Um, that eat animals. Those are also modified leaves. And lastly, cactus spines are modified leaves, so I just want to make a quick note here. Remember, thorns are modified stems thes cactus spines, air modified leaves so they may seem like more or less the same structure. But they're coming from different sources. Now that's all I have for this lesson. I'll see you guys next time.