The Structure of a Plant

There are many different kinds of plants. Some have flowers. Some don’t.

Some give us fruits. Some give us vegetables.

Some plants are poisonous, some have thorns and some are food for animals.

Even though there are so many different kinds of plants, there are several things about plants that are alike.

Let’s look at some of the ways plants are alike:

Plants start from seeds (most of them, anyway)
Plants have roots
Plants have stems
Plants have leaves
Plants need soil, sun and water to live
Plants make their own food (photosynthesis)
All plants give us oxygen

How plants are made

Almost all plants start from a seed. When the seed is planted in the soil, it germinates.

Here is how it happens…

Once the seeds are in the soil, they need water and warm soil to be able to take in oxygen and minerals from the soil and water through the seed coat’s tiny pores (holes) to give the inside of the seed the food it needs to break open and make its way through the soil so it can grow into a plant.

When the seed is full enough, it pops open.

The first parts of the seed to come through the seed coat are the cotyledon and the radicle (root).

The root takes hold of the soil and starts to take in food from the soil.

But because it is still so small, the cotyledon is still the main source of food for the seed.

The next part of the seed that appears is the hypocotyl.

The hypocotyl is sometimes called the understem because it first appears under the cotyledon.

The hypocotyl continues to grow upward with the epicotyl.

The epicotyl becomes the first leaves of the new plant.

By the time the epicotyl are showing, the plant is now above the ground.

When this happens, the cotyledon (which is sometimes called the seed leaves and looks like thin, dried brownish-white skin) has finished its job.

Because their job is done, they fall off the plant and become part of the soil.

Once the cotyledon are gone, the plant’s tiny leaves take over the job of supplying food to the new plant.

The growing plant

Once you have a plant with two sets of leaves on the new stem, the plant starts making its own food.

It continues to drink water through its roots, too.

The water also gives the plant vitamins and minerals it gets from the soil.

All of these things help to make the plant grow.

Plants don’t just grow on top of the ground, though.

The root system of a plant grows as the plant grows.

The main root that comes out of the seed is the tap root or main root.

It is connected to the stem of the plant and sends water and nourishment from the soil to the stem of the plant.

The tap root gets lots of help from the lateral roots.

The lateral roots also help to hold the plant in the ground.

The parts of the plant

The stem is the main part of the plant.

It is strong enough to hold the weight of the leaves and flowers and carries the water and nutrients from the roots to the leaves, flowers and fruits or vegies.

Without a healthy stem, a plant cannot survive.

Buds are the first thing to grow on the stem of a plant. Buds are little bumps on the stem that grow into petioles. The petiole is another name for the:

- Branch of a tree
- Smaller stems with leaves or flowers on the end of them

Leaves appear on the plant soon after the stem comes through the ground.

The leaves are responsible for making food for the whole plant to eat.

The leaves use sunlight, water (from the stem) and carbon dioxide (from the air) to make sugar for the plant to eat.

If the plant is a non-flowering plant, it will continue to grow and make more leaves over time.

If the plant is a flowering plant, the plant will grow and make more leaves, but it will also be working to make flowers.

If the plant is a flowering plant, the flowers on a plant appear after the plant has matured (grown up). In some plants, the flowers turn into fruits or vegetables.

In other plants, the flowers are ‘just’ flowers.

Every flower sits on the end of a stem. Some flowers (like tulips) have a single stem for a flower to sit on. Other flowers (like marigolds) have several stems; each with a flower on the end of it.

When we look at a flower we see the pretty colors and designs of the petals.

But did you know flowers actually have many different parts and that each part has a special job?

The receptacle is the green ‘cup’ the flower sits in.

The receptacle is directly connected to the stem.

The colorful parts of the flower are called petals.

Inside the petals of the flower you will find all the parts needed for the flower to make seeds so more flowers can grow.

The parts inside the flowers are:

The stigma and the style. The stigma is the tube in the center of the flower. The style is the opening of the stigma. These two parts together are called the pistal.
The stigma brings pollen up from the part of the receptacle called the nectary. The nectary is where nectar is made. These are the flower’s juices that bees take with the pollen to make honey.
Stamen are the thin tubes that surround the pistal.
Anthers are the fat tips at the top of the stamen. The anthers are covered in pollen.

Flower power

Use a magnifying glass to examine as many different flowers as you can find.

How are each of them different?