Two small plants, both about 400 million years old, are the oldest known examples of wood, according to a new study. The older of the two plants predates other early examples of wood by at least 10 million years.
Philippe Gerrienne, a geologist at the University of Liège in Belgium, identified the specimens along with colleagues from France and the United States. They describe the plants in the current issue of the journal Science.
Both plants are from the Devonian era, and the fossilized cross sections of the stems show rings of cells radiating out from the center, similar to tree rings. One specimen is 397 million years old and comes from Canada; the other, from France, is thought to be 407 million years old. Previously, researchers have debated whether wood evolved to help plants grow taller or developed as a way for plants to pull water up.
Because the recently identified plants were just a few inches tall, it is more likely that the wood served as a plumbing system to draw water up, the researchers write. Although the origins of wood remain a mystery, scientists believe that it is what eventually gave rise to large perennial plants.
The findings also support previous research indicating that wood may have evolved independently in different plant lineages and in different places.
Source: New York Times
