A five year effort to map the entire family tree for all plants-the most complete analysis yet of how the million species of plants in the world are related to one another-concludes that the many families of green plants living on land today descended from a single green "Eve," a near relative of which still lives today in pristine lakes as it did more than a few billion years ago. The new analysis involving more than 200 scientists in 12 countries, overturns long-standing theories about how the first single-celled algae advanced in size and complexity to become the showy trees and flowers that stand today at the pinnacle of plant evolution.