All About Seeds

All About SeedsSeeds come in different sizes, shapes, and colors. Some can be eaten and some can't. Some seedsgerminate easily while others need certain conditions to be met before they will germinate.Do you know that within every seed lives a tiny plant or embryo? You can hold in your hand 500 radishes, many thousands of petunias, or an entire meadow if you remember that each seed is a plant!

Seeds come in different sizes, shapes, and colors. Some can be eaten and some can’t. Some seeds germinate easily while others need certain conditions to be met before they will germinate.

Do you know that within every seed lives a tiny plant or embryo? You can hold in your hand 500 radishes, many thousand of petunias, or an entire meadow if your remember that each seed is a plant.

Each of these seeds is a tiny plant

Seeds travel! They can't just get up and walk to a new location, but structures on the seed may allow it to move to a new location. Some of the moving forces might be wind, water, animals, and gravity. Look at the seeds below and think about how they might travel from place to place.

Seeds travel! They can’t just get up and walk to a new location, but structures on the seed may allow it to move to a new location. Some of the moving forces might be wind, water, animals, and gravity. Look at the seeds below and think about how they might travel from place to place.

Seed Structure

The outer covering of a seed is called the seed coat. Seed coats help protect the embryo from injury and also from drying out. Seed coats can be thin and soft as in beans or thick and hard as in locust or coconut seeds. Endosperm, a temporary food supply, is packed around the embryo in the form of special leaves called cotyledons or seed leaves. These generally are the first parts visible when the seed germinates.Plants are classified based upon the number of seed leaves (cotyledons) in the seed. Plants such as grasses can be monocots, containing one

cotyledon. Dicots are plants that have two cotyledons.

Germination

 Some seeds require proper light also. Some germinate better in full light while others require darkness to germinate.When a seed is 

Seeds remain dormant or inactive until conditions are right for germination. All seeds need water, oxygen, and proper temperature in order to germinate. Some seeds require proper light also. Some germinate

better in full light while others require darkness to germinate.When a seed is exposed to the proper conditions, water and oxygen are taken in through the seed coat. The embryo's cells start to enlarge. Then the seed coat breaks open and a root or radicle emerges first, followed by the shoot or plumule that contains the leaves and stem.Many things can cause poor germination. Overwatering causes the plant to not have enough oxygen. Planting seeds too deeply causes them to use all of their stored energy before reaching the soil surface. Dry conditions mean the plant doesn't have enough moisture to start the germination process and keep it going.Some seed coats are so hard that water and oxygen cannot get through until the coat breaks down. Soaking or scratching the seeds will help break down the seed coat. Morning glories and locust seeds are examples. Other seeds need to be exposed to proper temperatures. Apple seeds will not germinate unless they are

held at cold temperatures for a period of time.

Nonflowering PlantsNonflowering plants like ferns reproduce by "seed-like" structures called spores. Spores are usually found on the undersides of leaves and look like tiny tufts of velvet. Spores are ripe when they easily fall off the leaf. You may want to try to germinate them but it takes a long time for germination and for a plant to develop.

What Is a Seed?In Case #1 you discovered that the seed of a plant allows it to reproduce--that is, make more plants like itself. Detective Le Plant has found that seeds come in hundreds of shapes and sizes. The purpose of all seeds is reproduction. Help Sprout and Bud discover the plants that come from the following seeds.

Which of the following plants grows from a pea seed (click on the picture)?

     

While you're solving the mysteries, pay special attention to these key ideas:

Seeds can remain alive over a long period of time, but they only grow when there are the proper conditions.

Some seeds have special structures that let them move from one place to another.

Seeds have different shapes, sizes, colors, and patterns.

Seeds have special needs that must be met to germinate.

Seeds have specific parts.