this is the preview video for chapter 45 on plant reproduction and development there are six sections in this chapter we'll Begin by looking at how plants reproduce then think about the structures and functions of flowers so angiosperms specifically we'll then turn to fruits and seeds we'll look at how seeds germinate we'll think about pollination and the various ways plants accomplish that and then we'll finish up by thinking about how fruits help disperse seeds when we talk about plant reproduction I want to remind you that plants can either reproduce asexually or sexually so most of this chapter is going to focus on the sexual reprodution but I want to show you some quick examples of that asexual reproduction this is one of those mother of thousand plants we actually have one sitting along the window in lab and you can see all of these new little things growing along the side um will fall off grow their own roots and those are going to be genetically identical Mother of Thousands to that parent plant so this was accomplished with mitosis not myotic cell division and we've also um already mentioned strawberry Runners so these elongated specialized stems that can grow out and begin to grow a new plant and you could actually sever that connection and the plant would do just fine we've already seen the alternation of generations but as a quick reminder we're looking at a diploid sporify and this is typically the plant that you um see that's like the large version of the plant and that will go through meiosis and produce um spores those spores are hpid they only have one copy of every chromosome they grow into a gapy those kopites produce gametes um eggs and sperm and those eggs and sperm come together in fertilization to make a new diploid zygote that grows into that diploid sporify here's a quick picture about Fern spores um so the external part of the gapy um is actually free living in ferns it's not in all plants so we mentioned that these um little pockets of spores grow typically on the underside of fern leaves um this is what those packets look like when they um uh open up you can actually get development into this free living gapy stage that would then produce gamage and when they fuse would make the diploid sporify version so that Fern you see in the forest is the sporify this little guy um is very very small like a fraction of the size of your pinky fingernail this is just a quick picture looking at um the sporify uh dominance in seed plants again I just want to remind you that the mature um sporify is typically what we look what we think about when we think about different plants so now we'll start to think about the gapy generations and in a lot of angiosperms these are not free living but tucked inside the other larger sporify um plant body the female gyes um are typically in the flower and um where uh we have the eggs developing there will be some other support cells as well we'll see those in a couple slides the male gapy is the pollen grain you can see here um that have landed and there are some other support cells associated with the pollen as well as we think about the structure and functions of flowers I want to remind you quickly that there are two different classes of plants that have seeds so gymnosperms and angiosperms both have pollen and both have seeds but when we're talking about flowers in this chapter we are going to be focusing exclusively on angiosperms a lot of angiosperms are animal pollinated so using things like different types of insects or Birds um bats are actually a really common um animal pollinator as well and this is by far the dominant um uh strategy for plants has been really really successful so natural selection has made a lot of variations of this um wind pollination does happen but it's only um in about 10% of angiosperms and you can't really control where your pollen is going as well with the wind as you can when you have somebody moving the pollen around so um that's why it's is probably not quite as common it's a little bit less efficient in this chapter we'll also think about parts of the flowers so we'll be looking at the seil um these green um uh Le they look similar to leaves they're not actually leaves that typically protect the flower Bud as it's forming the petals that you're probably familiar with we'll be thinking about the carpal which are housing some of the female reproductive parts with the ovary and ovals inside we'll look at some of the um male reproductive parts the staman with the anthers where the pollen grains are going to be developing and the filaments that are holding those up we'll also look at the stigma um where the pollen will be landing um when fertilization is about to happen and this is considered a complete flour it has all of these parts some angiosperms also have flowers but they're called incomplete flowers because they don't have one or more of those parts um all on the same flower so something like grass for example often lacks both petals and seil although they do still have um things like the carpal and the anthers to um move the pollen around there are also some plants that separate the male and female reproductive parts in their um flowers so pumpkins and zucchini for example actually have separate female flowers and male flowers and only the male flowers make the pollen and you can probably guess that the seeds um and the fruit are developing from the female flowers and you can actually see a little new zucchini forming there we'll also look more closely at the development of the male and female gyes so we'll be looking at um the male gyes and thinking specifically about the series of cell divisions so we'll be talking about the microspore Mother cell that goes through um my and makes some microspores and then how that eventually matures into a pollen grain that not only has um the uh actual sperm cells there are two of them in every pollen grain but it's going to have a tube cell as well and this will help it um uh go from the stigma and borrow in um and complete fertilization we'll also be thinking about the female gapy development um similarly there is a mega Spore um Mother cell that goes through meiosis and makes um megaspores and then another series of cell divisions that ends up with one egg cell and um some other cells that aren't going to actually develop um into seeds plants have this really neat strategy called double fertilization and we just mentioned that pollen grains actually have two sperm inside each pollen grain and both of those are going to be critical so when the pollen grain lands on the stigma of a carpal one um it's going to like send down that pollen tube um which is necessary to actually transport the sperm to where the ules and the eggs are so both of these sperm are going to be critical um one sperm is going to fertilize the egg um and that's going to develop into an embryo make a new sporify generation The second sperm um enters this other large cell and fuses with some of those other nuclei present and that's going to make the endosperm which is that um storage of all that extra food that that seed is going to be using um to give the new sporify generation um a jump start so that's a good segue into thinking about fruits and seeds so um we'll be looking at the different parts of fruits um so you typically eat a lot of different fruits even if you think of them as vegetables uh according to botnus they are fruits and so here's a quick picture of a pepper plant and you are actually looking at um the mature uh ripened ovary um containing the seeds inside when you think about a um pepper plant um fruits are not always edible there are a lot of different ways that fruits can um uh be distributed um you know some plants uh have Edible Ones to try to help encourage animals to eat their seeds but there are a lot of different ways as well we'll also be looking more closely at seed development um we've already briefly talked about the parts of a seed um including the tough seed coat um we have the endosperm we have the calans which are like the new um developing um uh chots and these are going to be really important um for the plant as it starts to germinate we'll also talk about some um brief differences between um diecuts and monocots when we think about how seeds germinate and grow you probably know that germination is when that seed is actively um sprouting um but there are a lot of things that have to be in place for that to happen many seeds go through a period of dormy to make sure that they don't Sprout too early before conditions are really ready um for them to uh take hold and grow well so dorcy cues can include things like a period of drying out some um seeds actually need a period of cold before they can germinate and that's really common um in plants that are native to temperate areas like um the Eastern us where we go through cold Winters and some plants also need to have their seed coat disrupted in some way and again all of these things are trying to ensure that a seed doesn't start to germinate too early when we talk a little bit more about um seed uh sprouting and in germination we'll be looking at some different structures and including um uh parts that are helping protect um that seed as it's pushing through the soil initially so we'll be talking about um epical and hypoc codal hooks which are just going to be sort of protecting these very tender parts as they move up through the soil we'll also spend some time looking at um plants and pollinators there are a lot of really cool examples of co-evolution and when we think about um animal pollination there are several different strategies that plants have mimicked so sometimes they offer um food um they offer at least the perception of uh sex with an insect so this is actually a species of orchid that mimics um the structure of a female wasp there are even some um pheromones um and other scents that seem uh very similar to wasps so that will bring in the male wasps and some plants are essentially used as a nursery where um other insects are laying their eggs I won't go into these in a lot of detail in the preview but we'll be looking at some plants um both native um to the US um this is a yucka plant um and it's essentially used as a nursery for some species of moths they lay their um eggs here and then their caterpillars are using part of the seeds and we'll talk about figs figs have a really cool um way of being pollinated also by wasps and we'll wrap up with looking at how fruits help disperse seeds so Evolution has really favored plants that at least sometimes have the ability to spread their seeds out pretty far away from where that original um plant was and this not only helps them spread um in a particular terrain but it's an extra insurance because if something happens to that original habitat but there are some members of that species that are pretty far away they have a better chance of surviving we've already Ted talked about some of these dispersal methods a little bit we know that some fruits include things like Furs which can stick to animal fur we know that some fruits um taste really good to at least particular species this is a cedar waxwing bird um eating a berry and we'll also look at um some strategies like uh explosive Natures of fruits this is a a plant that's native to the eastern US jewelweed um it's found like you know in a ditch like along the side of the road um just near my house and when you touch these seed pods they burst open um and like kind of like you know throw their seeds which is really neat you probably already know about um some fruits that are being wind dispersed so um things like maple trees um that make um polos that kind of flutter down and we'll also mention um water dispersal this isn't super common a lot of fruits can float for some period of time but um things like the coconut um have really mastered this and coconuts can actually travel pretty far from the parent palm and that is it for the preview of chapter 45