Education Program

Why Do Plants Have Flowers?

Flowers are used by a plant to have kids....er.....seeds, and new baby plants. Male parts of the flower make pollen, which is a yellow dust that contains all kinds of information on being a plant just like Dad. Female parts make ovules, which contain all kinds of information on how to be just like Ma. Nature likes to mix information from both parents when it makes a kid; it's the same for plants as it is with animals. If the information didn't get mixed, all the kids would be identical to the single parent who made them... all the flowers would be the same shape, the same height, the same color.....BORING!

The problem...how do you get the pollen and the seed together? It is not like they can get together in the same place like animals. Imagine a strange rose bush pulling up to your garden gate and asking the plant in your yard for a date? Tell the bush to have her back by 10.00pm and keep his thorns to himself? Nah....

So plants reckoned.. "If I can't move from this spot, why can't I get someone else to carry my pollen over to that nice little sapling over there, swaying in the breeze." But how??

The plants have found several way to do it. Oak trees and pine trees use the wind, scattering their pollen in clouds hoping that some would hit where needed. Others bribe insects to carry the pollen away. The bribe is honey money, so to speak. The insect, perhaps a bee, is attracted by the fragrance of the flower, which tells it that there is nectar to be had. Nectar will become honey in the bee's hive. So the bee does a quick sniff, or maybe is tempted by the bright color of the flower, and arrives for the free gift.

But not so fast, Ms. Bee. The nectar is hidden way, way down, and you are going to have to climb right down deep inside, amongst those sticky-up stamen things. And Mr. Bee gets covered in the pollen which is produced on the stamens. Stamens are the male part of the flower, which produce the pollen, which has all the information on the Dad-part of the flower. So, after visiting flower number one, the bee goes to visit flower number two. And some of the pollen from the first flower gets spilled into the second flower. The second flower might also give some pollen to the bee, but with luck, some of the pollen from the first flower will land on the stigma. The stigma is the female part of the flower, and is designed to carry the pollen down to a deeply hidden ovary at the base of the style, which is a tube connecting the ovary to the stigma.

Can a flower be both Ma and Dad at the same time? No problem. In fact some flowers can actually fertilize themselves, while others are just female or just male like us human types. But most flowers don't want to be a mirror image of a single parent, which is how they would end up if they mixed the pollen and ovum (the female part of the seed-to-be) that they had produced themselves. If all the flowers in a field were exactly the same, and one got sick, then maybe they ALL would get sick if they were exactly alike. The plant puts its female and male parts in places where it would be hard for a single insect to mix the pollen and ovum from the same plant. The plant often forces a visiting insect from another plant to put the pollen on the stigma before it can reach the pollen on the stamens. Vive La Difference!

Yes. Well Anyway....

Let's take a look at how the flower is constructed. I will only show you one particular flower design, but they mostly use the same general layout. From the outside you see the petals and the sepals.

Let's pull two of the petals off and look inside!

Remember that the female part of the flower is in the very center, and is called the carpel or pistil (pssst! botanists never agree on the name of anything, and come up with real WEIRD words anyway!!!). The male stamens are in a ring around the carpel (or pistil).

Now we will take a closer look at the carpel - pistil and the stamens. The pollen is made in the special anther cells at the top of the stamens, and the filaments help arrange them so that the flower does not pollinate or fertilize itself. The ring of stamens is called the androecium. The stigma at the head of the style receives pollen (the process is called pollination), which moves down the pollen tube to the ovary, where the female part of the flower has produced an ovum. The pollen combines with the ovum, fertilizing it and making a whole out of the seperate Ma and Dad parts of two different plants. The result is a seed, which is really a complete plant waiting in a shell for the conditions to be right for sprouting. Just add water, warmth, and the kids grow.

Let's take a peek at an insect entering a flower. See how the insect, a moth of considerable artistic deficiency in this case, is entering the flower and touching just the stamens, but not the carpel. It is possible that the last flower puts pollen on the moth's rear end ("the bug butt" to kids unfamiliar with insects), so it will spread the pollen on the stigma while receiving new pollen from the stamens.

BYE...HOPE TO SEE YOU AGAIN!