The announcement was made on Wednesday at the International Botanical Congress in St. Louis. Researchers working on the Deep Green project announced they have discovered that all green plants trace back in direct linear fashion to a common ancestor.

Deep Green, a six-year effort involving more than 200 plant biologists in 12 countries, said it has developed a framework for identifying the relationships between all the green plants on earth.

"The goal is to have a very complete picture of the tree of life," said Brent D. Mishler, a co-principal investigator for the project as well as a professor of integrative biology and director of the University and Jepson Herbaria at the University of California, Berkeley.

"Just as an artist starts with a sketch and then fills in the details, we now have the basic framework and can begin digging into the finer and finer scale."

It was previously thought that throughout history various families would have evolved and left descendants, so that today we would see distinct subgroups related only in the distant past, explained Mishler. Instead, at each stage of evolution only one family or lineage seems to have survived.

"It seems that only one lineage actually made it," Mishler said. "This indicates there's an Eve in the primordial soup."

"This is a project of enormous intellectual importance," said Leonard Krishtalka, director of the University of Kansas Natural History Museum.

"It's critical for understanding the evolutionary relationships among the green plants so that we can make intelligent assessments about scientific issues and conservation issues."

According to Mishler, understanding the interrelationships of plants will help scientists predict which plants might have qualities such as medicinal value or pest resistance.

"If you have an organism that's potentially harmful or helpful, the most useful thing is to know its relationships; this will help you predict its traits," said Mishler. "If you're looking for a cure for cancer, you don't want to go out randomly and look at every plant in the forest."