Tuesday, March 11, 2008

What Is A Flower?


All plants produce flowers for the same reason: to make seeds so another plant can grow. Pollination : Flower markings are like the landing lights on an airport runway. They guide the bee into the flower's pollen grains Bees can help flowers make seeds.
Bees usually look for pollen and sweet juice. Every flower has pollen, although some flowers don't have sweet juice. The bee's first job is to move pollen from the anther of one flower to the female stigma of another flower. An anther is the male part of a flower that has pollen grains on it. A stigma is the female part of a flower that receives the pollen. In other words, when a bee gets pollen from a flower, the pollen sticks to the bee.
The bee goes to another flower and the pollen falls onto the stigma. Most flowers use this pollen to make seeds. Other flowers use their own pollen to make seeds.
Each tiny pollen grain grows into a long tube. These are called pollen tubes. They grow until they come to the ovary. The ovary is the section of a flower where the pollen tubes meet. Now a male gamete from the pollen tube joins the egg from the ovary and a seed is born.Spreading SeedsSome seeds are spread by animals' feet. Charles Darwin once grew 80 plants from the mud he scraped off a bird's foot A seed has everything it needs to produce new plants. No seed can grow with the fruit around it. A seed has to have enough water, good soil, and sunlight. Sometimes people plant them and other times the seeds get planted on their own. People also put seeds in gardens or fields, and water and fertilize the seeds.
Birds help some fruits like the cherry by eating the fruit around the seed. The mistletoe's seeds are covered with a sticky substance that sticks to the bird that tries to eat it. The mistletoe's seeds have to land on the tree or they die.
Some seeds travel by sailing in the wind. Others float in the water to get to the land. Others hitchike on animals. Some just get blown in the wind. Seeds can also grow in a flower and drop to the ground. When the seed leaves the flower or whatever it was in, it's called dissemination. This is one of the most important steps in the seed's life. Some tree seeds drop directly below the parent and die because there is not enough light or food for them to grow.
The seeds that travel by wind must be light-weight. Some of these seeds have wings, like the maple seed. Some of these seeds have gone 32 miles on a windy day. Another flying seed is the dandelion which gets planted because ants carry the seeds down into thier hole.
The water travelers float away from their parent trees. Coconuts may drift for several months and travel for up to 1,200 miles (2,000 km) before reaching dry land. The coconuts are able to float because of special fibers around their seeds.
The hitchhikers are built with spikes. They get stuck to animals and eventually fall off. Some seeds have a sticky substance that makes them stick to animals. Then they travel to another place to grow.
Some plants have sacks that explode. The squirting cucumber bursts open and shoot its seeds up to 27 feet (8m) away from the parent plant. The seeds zoom off and may travel as fast as 62 miles (100km) per hour.

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