before it's in the papers"
August 03, 2010
TO THE WORLD SCIENCE HOME PAGE
Finding sheds light on origin of flowers
and World Science staff
Flowers are found almost everywhere, but the origins of flowering plants are far from understood: Charles Darwin called the problem an “abominable mystery.”
An analysis of a plant that seen as a “living fossil” now suggests the first flowering plants arose during a time of intense evolutionary experimentation, a researcher says.
The plant, found in the rain forests of New Caledonia in the South Pacific, has a unique way of forming eggs, said William “Ned” Friedman of University of Colorado at Boulder, who conducted the study.
This quirk, he added, suggests the plant may represent a missing link between the remarkably diverse flowering plants, known as angiosperms, and their yet-to-be-identified extinct ancestors.
Angiosperms are thought to have evolved from gymnosperms—the prevailing land plants when dinosaurs reigned in the Cretaceous and Jurassic periods—around 130 million years ago. They have become the dominant plants on Earth today.
The finding focuses on the egg sac of Amborella trichopoda, a relic species remaining from an ancient lineage. During development, the female part of its reproductive apparatus, called the embryo sac, has an extra sterile cell accompanying the egg cell compared with most modern flowering species.
That’s “akin to finding a fossil amphibian with an extra leg,” according to a commentary published in the May 18 issue of the research journal Nature, where Friedman’s study also appeared.
Amborella’s peculiar egg-forming structure may eventually link the odd South Pacific shrub to gymnosperms such as conifers, said Friedman. “We associate this structure with a relatively primitive reproductive process.”
The finding suggests flowering plants may have arisen during a time when plant evolution was “particularly flexible,” Friedman said. That may have allowed for the evolution of the seemingly costly business of making flowers.
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