Gymnosperms produce naked seeds. Basically, that just means that they're not enclosed by an ovary, like angiosperms. Seeds of gymnosperms are usually packed into cones. And as we were talking about earlier, generally, most plants will have the male and female sporangia. Right? The male cone and the female cone on the same plant. We call these monoecious plants. Some plants, however, are dioecious, and you'll actually find the male and female sporangia on different plants. So those male and female cones will be found on different plants. They won't be found on the same individual. Conifers are probably the gymnosperms you're most familiar with. These are like pine trees. And they're basically the group of gymnosperms that have those distinctive needle-like leaves. Right? What, you know, we think of as just pine needles. I mean, there are many different types, but that's a feature that defines the conifers. And also their sporangia are contained in those cones which are technically called strobilae. Now the cones are actually modified leaves, right? They're sporophyll. And the pine needles represent an evolutionary modification of the leaf that has a very thick cuticle. And this helps these plants prevent water loss because, you know, conifers, I mean, there are conifers all over the place but they can live in areas that have restricted access to water. So these pine needles allow, and especially in the wintertime, they live in cold places where it can be very hard for the roots to obtain water due to frost and the freezing temperatures. So these pine needles are an evolutionary trait that allows them to really prevent water loss, very effectively.
Now, let's take a look at the life cycle of a gymnosperm. When the pollen grain reaches the ovule, it's actually going to germinate and form what's called a pollen tube that digests its way through the megasporangium. So here we have our pollen grain. It's gonna get to our ovule and then here, you can see the pollen tube digesting its way through the ovule to the megasporangium. Now the megasporocyte is going to undergo meiosis and produce 4 haploid cells. One of which will become the megaspore. And the megaspore will actually develop into a female gametophyte containing multiple eggs. When the pollen tube reaches the eggs, it's going to eject sperm that will fertilize the egg and then the ovule will become a seed. And after fertilization, of course, we're gonna have the formation of the embryo. And that is our little seed right here. It's resting on one of the scales of the cone. So if you look at a pine cone, it has all these little scales, these little, I mean they're like little diamond-shaped things in the figure but, you know, they're little cone scales. Well, if you were to peel that back and look at it, that's where the seed develops, right? That's where your seed is going to be. Now, the seed, of course, will get carried away and sprout into a sporophyte and that is what grows into these big hulking trees that of course will develop their male and female cones and repeat this cycle over again. Don't worry too much about memorizing all the aspects of the life cycle of gymnosperms. We're gonna cover that in much more detail when we take a deeper look at plants. This is just meant to be sort of a broad strokes overview.
With that, let's flip the page and talk about angiosperms.