Hi. In this video, we're going to talk a little bit about nonvascular plants. Nonvascular plants or bryophytes, as they're technically called, are plants that include mosses, liverworts, and hornworts. You can see a phylogeny of this right here. We have the Embryophytes, which includes all the different types of plants we'll be talking about. And then here, we have our bryophytes. You can see that vascular plants are a separate lineage. And remember that the defining feature of these organisms is that they don't contain vascular tissue reinforced with lignin. Although some may have transport tissues that use cellulose to maintain their rigidity. You can see an example of moss, liverwort, and a hornwort, right here. Don't worry if you can't really tell these apart; I mean, hopefully, you've seen moss before, if you've never seen or heard of liverwort or hornwort, not a big deal. These are just little, low to the ground, very simple, extensive nonvascular plants. Now, as we previously discussed, they have a gametophyte-dominant life cycle, which is going to change in later lineages to a sporophyte-dominant life cycle. And these organisms are also homospores, meaning that the spores they produce are all of the same type. Some species have bisexual gametophytes, meaning that the male and female reproductive, or the male and female gametophytes rather, are located in the same plant. Some species, like mosses for example, have separate male and female gametophytes. So the male parts and the female parts are found in separate plants. Here we have an example of a moss life cycle. And we can just kind of use this as a stand-in for our nonvascular plant life cycle. So I'm just going to quickly walk you through this image; jump out of the way here. So spores give rise to the gametophytes. Right? And here we have our male gametophyte, here we have our female gametophyte. It's through mitosis that these spores will develop into the gametophytes. Here you can see we have the fully developed male and female gametophyte. And you might notice there's actually an error in this diagram. I didn't make it. It's really not a big deal, but you know, here it says female, and here it's male. You know, these arrows should be reversed; sorry. I didn't make the figure. But it shouldn't really affect your understanding. Obviously, the female gametophyte spore is going to develop into the female gametophyte and the male gametophyte spore is going to develop into the male gametophyte. So just remember that these arrows are crisscrossed. Anyhow, these gametophytes are going to produce the sperm and the egg. And remember that the sperm requires water to get to the egg. And the structure that produces the sperm is called the antheridium, the structure that produces the egg is called the archegonium. Don't worry; we're going to go over this again on the next page. So when the sperm and the egg get together, we're going to have fertilization. A zygote is going to form, right, and that is going to develop into an embryo. And everything on this side, remember, except for the zygote here, needs to note that zygote is 2n. All this other stuff is n. Right? And it's indicated in the figure that these are all haploid. All this stuff, of course, except for the zygote. Right? The zygote's diploid. They don't actually show it in the figure, but when the sperm and the egg combine, they're going to form the zygote. So everything over here is diploid. Diploid. Right? So this is the dominant part of the life cycle. Basically, what that means is the part of the plant we're used to seeing is going to be this haploid gametophyte part of the plant. This embryo that forms after the sperm gets to the egg, this embryo is going to sprout into this sporangium. Right? So this embryo, basically, is going to develop into the sporophyte. And the sporophyte, part of the sporophyte is the sporangium, which produces the spores. And those spores, remember, are going to be haploid, and the sporophyte produces them through meiosis. Those haploid spores then develop into the gametophyte and we repeat this cycle. So, you know, this is just basic alteration of generations. The things to bear in mind are that water is necessary for the sperm to get to the egg. And those terms antheridium and archegonium, don't forget, we're going to talk about those in just a moment. So with that, let's flip the page.