Gynosperm Reproduction

What is a gymnosperm? ____________________________________

What is reproduction?______________________________________

The reproductive part of a gymnosperm is called the cone. Did you know cones can be male or female? Male cones are fuzzy and smaller than female cones. Male cones produce pollen. Each grain of pollen contains two tiny sperm cells (the male reproductive cells.)

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The pollen grains have tiny balloons that help them float through the air. They have to be able to float a long way so they have a better chance of finding the female cones. Many pollen grains don’t make it very far, so the plants have to release millions of pollen grains. Most of the pollen ends up not finding a female cone and ends up all over the ground and other plants.

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The pollen grains that land on a female cone attach themselves to a part called a scale. The scale contains two two female parts called ovules. Inside the ovules are eggs. When the pollen gets stuck on the end of an ovule, it grows a tube to the egg. Only one of the two sperm can enter the egg. Mother nature is very competitive.

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When the sperm joins the egg, a zygote is formed. This is a single celled organism. Then the zygote cell begins to divide and it turns into an embryo. The ovule around the embryo becomes hard to make a protective covering. The embryo now becomes a seed. When the seeds are ready, the female cone opens and the seed drop out. This whole process takes two years.

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The seeds do not have to start growing immediately. They can wait many years to germinate. Some pine trees only drop their seeds when there is a forest fire. During the fire the cones open and drop the seeds. After the fire, all the trees a burned down making room for the new trees to begin growing.

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Questions:

1. Which cones produce pollen, male or female?

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2. What is inside the pollen?

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3. What happens to most of the pollen?

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4. Where are the ovules located?

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5. What is inside the ovules?

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6. What happens when the sperm joins the egg?

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7. What does fire do to some pines?

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Plant Reproduction

How do plants reproduce?

Flowers not only look pretty but, in fact, are important in making seeds. Flowers have some basic parts. The female part is the pistil. The pistil usually is located in the center of the flower and is made up of three parts: the stigma,style, and ovary. The stigma is the sticky knob at the top of the pistil. It is attached to the long, tubelike structure called the style. The style leads to the ovary that contains the female egg cells called ovules.

The male parts are called stamens and usually surround the pistil. The stamen is made up of two parts: the anther and filament. The anther produces pollen (male reproductive cells). The filament holds the anther up.

During the process of fertilization, pollen lands on the stigma, a tube grows down the style and enters the ovary. Male reproductive cells travel down the tube and join with the ovule, fertilizing it. The fertilized ovule becomes the seed, and the ovary becomes the fruit.

Petals are also important parts of the flower, because they help attract pollinators such as bees, butterflies and bats. You can also see tiny green leaf-like parts called sepals at the base of the flower. They help to protect the developing bud.