Double fertilization is a complex fertilization mechanism of flowering plants. This process involves the joining of a female gametophyte with two male gametes. It begins when a pollen grain adheres to the stigma of the carpel, the female reproductive structure of a flower.
Answer: Paleozoic
Explanation: The Paleozoic Era, which ran from about 542 million years ago to 251 million years ago, was a time of great change on Earth. The era began with the breakup of one supercontinent and the formation of another plants became widespread. And the first vertebrate animals colonized land.
