Seeds

How does a little plant seed turn into a great big tree? Well, all great things have small beginnings, and plants are no exception. The development of a seed begins with fertilization. The pollen grain will deposit sperm into the AV you'll on the flower. And this results in embryo genesis, which is the development of the seed and more importantly, the plant embryo within seed. Now, after fertilization, what you're left with is a zygote. And this zygote is going to divide into two daughter cells known as the A pickle cell and the basal cell. So here we have ours. I go and it is going to divide into a pickle cell. And this basal cell, now the a pickle cell is going to form a massive cells that will eventually basically become the plant. This cell mass will differentiate into those primary mirror stems. We talked about the pro today ERM, Ground Mary stem and pro Camby in, and you can see the A pickle cells division as it continues along to the structure. And eventually just, you know, it's growing into this mass of cells, which will eventually form the plant embryo that see behind my noodle here. Now the basal cell forms a structure called the suspense ER that contributes to support structures for the embryo Onley. One cell in the SSA Spencer will actually contribute to the plant embryo. So here we have our suspense. Er, now these embryonic plants have embryonic leaves. We call them CO Tilden's, and plants will actually be differentiated into Monta cots and die cots. Depending on how maney Cutillo dons, they have Monica cots have one until it on right mano, meaning one and you die. Cots have to Attila dons die meaning to. And if you're curious, the you part here is, uh, means true. So these it's saying, basically to true leaves or Kotil Iran's. Now the embryonic plant has some other structures that we should go over. Uh, these include the hyper Kotal, which you can see here we jump out of the way. That is basically the embryonic stem of the plant. So it's this portion here. It also will have a radical, which is an embryonic root, and here you can see our radical. Now, looking at these two seeds over on the left, you'll notice that, uh, that these are differentiated as Monica and Die Kat. So here we have a Monica seed in here. We have a you die Kat seed and you can tell based on the telethons. This one has just one. This guy has to, and you can see the other seed parts, including the seed coat, that protective outer layer, the endo sperm, which is going to be the nutrients that the embryo feeds on. And also we'll have this structure here called the epic Cottle, and that is something that some plants have. It's kind of like an embryonic stem, but it's an embryonic stem that extends beyond the cattle A dons. So, uh, when our plant sprouts, this becomes more readily apparent, and we'll actually talk about sprouting when we flip the page.

once our plant embryo is formed and our seed is all set still has to somehow turn into a fully formed plant. This begins with germination, which is the process by which a plant forms from a seed, and it usually occurs after water is absorbed by the seed through a process known as imbibe Bishan. Now the seed coat, as we've said before, is that protective outer layer and it forms from the Integra mint, which, you might recall, is a structure found in the AV you'll now that outer layer is tough. And so, while sometimes in division will be able to cause enough swelling that it can break the seed coat open and sort of free the plant Thio uh, develop some seed coats are actually too thick to absorb water and require some type of physical penetration in order to Germany. In some cases, this could actually require being, you know, for example, like chewed up and digested a little by an animal or something before the seed can. Actually, Germany now the way a seed will sprout depends on whether the plant is amon a cot or you die. Kat, you die. Cots will have ah, hyper coddle that curves and grows towards the surface and essentially pushes the cotillions out of the soil. So you can kind of see that happening in this diagram here, where this hyper Kotal will be curved and it will grow up and push its way out of the soil. And once it's out of the soil, the CO. Tilden's will actually sprout out of this seed. Now in Monaco, it's This happens a little different. Monica cots will actually push their shoots straight up through the soil, whereas in the case of you die cots thes hyper Kotal right, that embryonic stem is curved and you can almost think of. This is like a process of the plant, like arching its way out of the ground in Monaco. It's This is more of a straight shot, and because of that, Monta cots actually have to have these protective structures that help their emerging roots and shoots. And we call those the Kolia, Rizza and Kulyab Tile depend. Um, and the call your ISA is the first structure to actually emerge from the seed. Hop out of the way here, concede it here, and it is protecting the radical and you might I hope you caught the spelling mistake in this figure. Radical is supposed to be spelled like that. I just like the spelling mistake too much to take it out of the figure because this is basically spelled like, you know, like radical dudes. So anyhow, the polarizer protects the radical, and the Kohlhepp tile protects the flotilla dons, which you can see as thes little structures here inside the kaliope tile. Now, hopefully, as you can see in this image here, here's our seed. It's going to stay where it is, and from here, it's shoots, they're gonna push up, and its roots are gonna push down. So whereas the you die, Kat again did that curving, pushing out of the soil, right? This is gonna have the seeds stay where it is, and it's gonna push it shoots and roots out from that point. Now, how do these seeds get where they need to go? Well, seed dispersal is the technical term for the transport of seeds away from the parent plant. And there is a number of ways this can happen. Uh, you can have wind dispersed your seeds, water also animals as we can see with this dog here that is covered in bors, which are seedpods for plants now. Oh, and here also, you can see these little plumes from a dandelion. Here is the seed, and this tuft on top is to help it help the seed be dispersed by wind. Now, seeds don't germinate right away. When they land in dirt, they actually can enter a period of dormancy. And we'll actually wait to germinate until the conditions are favorable. And in the case of some seeds, this could be years of dormancy before germination. All right, let's turn the page.

one way to encourage animals to disperse your seeds aside from having them stick to your for is by putting them in fruit. Which, of course, is delicious. And we animals love to eat, So fruits are technically these seed bearing structures that form from the ovary after flowering. Now, as you can see in this diagram here of a peach or it really could be any stone fruit, you have your seat on the inside there, with its endo sperm embryo and seed coat familiar structures to us and then surrounding it. In this area we have what's called the Pere carp, and this is the part of the fruit that we eat. And this is what ripens from the ovary and will surround of seeds in a sweet, delicious coding. No, as I'm sure you're aware, there are many different types of fruit, and they take all sorts of shapes and sizes, and in fact, we call a lot of fruits vegetables, even though their technically fruits, for example, zucchini technically fruit, right? It's got that ripened of aerial ovarian walls surrounding seeds. Not that sweet, which is why we call it a vegetable. But technically it is a fruit. And, of course, amongst fruits that we think of his fruits. There's a ton of variation, and what we'll see is that these are actually due to different types of development. So you have simple fruits and these air fruits like Cherries they developed from a single flower with a single Karpal or if used car pulls. So a single pistol or single Karpal and these will have a simple structure like a cherry, that ovarian wall surrounding the A little seed in there and this forms from again one flower with its single pistol. We're single, Karpal. Now you can also have aggregate fruits which developed from single flowers that have multiple carpools and an example of this is the raspberry. So even though this develops from a single flower all of these little, uh, juicy balls in the all right, maybe I should think about my phrasing there. All of these little morsels in the raspberry, um, form from separate carpools and they each have a seed in them. Those are again called aggregate fruits. You also have multiple fruits which developed from multiple clustered flowers. And a nice example of this is the pineapple which you can kind of see in its structure how it would develop from clustered together flowers. And lastly, we have accessory fruits, which developed from ovary tissues as well as tissues outside the carpal. And a nice example of this is a strawberry, which has its seeds on the outside and has it's delicious Freedy meat inside the outer coating of seeds, so many different types of fruits that result from different types of flowers. And that's all I have for this lesson. I'll see you guys next time.