Why Plants Have Flowers
Flowers are some of nature's prettiest creations. Just take a walk outside -- there are so many to see! They come in many different sizes, colors, and shapes. If you think about it, they are kind of like people that way. But have you ever wondered why there are so many different flowers? In fact, why do plants have flowers anyway? It could be that flowers blossom so that people like you and your friends have something pretty to look at and smell. That sounds really nice, but that isn't why plants have flowers. They actually grow for a really cool reason. They want to have babies! Okay, so plants don't really have babies, at least not like humans do. Plants do need to multiply and make more plants like themselves. To do that they need seeds. That's where flowers come in: They help plants make seeds!
Both the male and the female parts carry important information that the new plant will need to grow and basically be a plant. The type of information depends on whether it comes from the male or the female part. The information that comes from the male part of the plant is in the pollen. That's right -- pollen! The information that comes from the female part of the flower comes from the ovules. The tricky part is getting the pollen to the ovules so that they can combine information together for the new plant that they'll make. To do that, a little help from nature is needed.
Plants have a bit of a problem when it comes to getting pollen to other plants so that they can reproduce, or make more plants. Since they can't pull up their roots and walk where they need to go, they depend on insects and animals and even the wind to do the hard work for them. Windy days are great for flowers and the spreading of pollen. On windy days, gusts of wind may blow pollen to other flowers. But what about insects? Insects need a little bit of motivation to help out. This is one of the reasons flowers are so colorful and why they smell as good as they do. Certain insects are attracted to the color of a flower's petals. Some insects like the way a flower smells. When the insect lands on this sweet-smelling and pretty flower, it gets a bonus for its effort in the form of nectar. As the insect (which can be something like a bee) makes its way to the nectar, it has to touch the pollen on the male part of the flower. This part is called the stamen and it is covered in pollen. The sticky pollen clings to the legs and body of the insect. But don't worry, it doesn't hurt it and the insect really doesn't mind so much.
The pollen needs to get to another flower and the plant is depending on the hungry insect to do the work. When the insect flies to another flower, it rubs against the female part of the plant and pollen falls off. This female part is what we call the stigma. The stigma is connected to a tube called a style. The style is also connected to the flower's ovary. The pollen travels from the stigma to the ovary.
Whew! That sure was a lot to say, and it might be a lot to understand too. Sometimes it is easier to understand when you have a picture to look at. A picture can show you the parts of a flower, starting with the outside of it. In this picture you'll see a closed flower. The colorful part of the flower is its petals. The small leaves at the base of the petals are called sepals.
The petals protect the inside of the flower. The inside is where you'll find the male and female parts that we mentioned earlier. If you remove several of the petals, you'll see the center of the flower is the female part. The entire part is called a pistil or a carpel. This pistil includes the stigma, the style, and the ovary. Around the pistil are the male parts. As noted, this is called the stamen. At the top of the stamen is a fat structure called an anther. The anther is where the pollen is made. It is held upright by a thinner stalk called a filament. The filament keeps the anther away from the pistil so that the flower does not fertilize itself. This is very important for plants because it makes each plant slightly different. If a plant fertilizes or pollinates itself, the new plant would be exactly the same as its parent! That means all of the new plants and the parent plant would be weak in the same way.
The following image shows an insect crawling into a pretty flower. As you can see, the insect is touching the stamen and picking up pollen as it moves. The pollen from this plant will be left on the stigma of the next flower it visits.
So how does that seed get made? When the pollen from the insect falls on the stigma it is pollination. The pollen moves down the pollen tube. The ovary at the base of this tube has made an ovule. When the pollen reaches the ovule it fertilizes it. Fertilization turns the ovule to a seed. The seed is a hard shell that protects and contains the baby plant. When that seed falls to the ground and the conditions are right, the baby plant will begin to grow and eventually turn into a new plant!