London: A study of 400-million-year-old samples of fossils has revealed that woody plants appeared about 10 million years earlier than previously thought.
The samples revealed rings of cells characteristic of wood, a team of scientists observed.
They also suggested that the woody substance appeared to be a mechanism to transport water rather than acting as a support to allow plants to grow taller.
Phillipe Gerrienne, a geologist from the University of Liege, Belgium, told BBC News that the samples are the first and, to date, only samples of woody plants that had been placed in the Early Devonian period.
“The Middle Devonian plants with wood are shrubs or trees of very small stature. Our plants are much smaller, herbaceous and probably 20-40cm (8-16in) tall,” he said.
“I would even say that our plants are smaller than some other contemporaneous plants. In fact, all Early Devonian plants were herbaceous, so externally, you would not be able to tell which had wood and which had not.”
He added that the ancient plant samples featured in the study would help researchers understand the first steps of “true wood” evolution.
The study has been published in the journal Science.