It may be time to rewrite a passage of the story of plant evolution—again. Paleobotanists have unearthed evidence that wood developed in plants earlier than was thought, but not for structural support. Two scientists and their students found secondary xylem in fossils of small herbaceous plants dating as far back as 407 million years, to the early Devonian. That makes them about 10 million years older than the woody, middle Devonian plant remains in which the oldest traces of wood previously were found.
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