Plants and Pollination

History: The very earliest photosynthesizing plants on Earth had only one cell, and they reproduced by mitosis: splitting themselves in half.

By about two billion years ago, some of these cells began to split themselves in a more sophisticated way, called meiosis, where there's a daddy cell and a mommy cell and each parent cell makes a new cell with a copy of half of its DNA. With all this mixing up of DNA, plants began to evolve much faster than they had before. Soon there were plants with more than one cell, likeseaweed

When the first plants like moss began to live on land ago, they developed a way to reproduce using spores instead.

Spores worked well for the moss, and also for the ferns that evolved later on. But these spores counted on falling on to wet ground; if they didn't find wet ground they just died.

When plants began to spread on far from the edges of streams, they needed a way to protect baby cells that fell on dry land. That's when the earliest plants gradually evolved hard covers for their baby cells, or seeds. Soon, there lots of seed plants, mainly pine trees, all over the land.

Beginning around the same time, a few plants were developing new ways to help out their reproduction: flowers, and fruit. Flowering plants needed bees to land on them and carry theirpollen from flower to flower. Bees and flowers evolved together, and they are symbiotic - bees can't live without flowers, and flowers can't live without bees. The earliest flowers developed as a way to attract insects and get them to help spread the plant's pollen far away from where the plant was growing.

Many plants, such as grass, weeds and even large pine trees, rely on the wind for pollination. The pollen is small and light, allowing it to be blown by the wind. The pollen lands on other plants and fertilizes them.

Why will a seed die if it grows directly under its parent?