A plant fossil that gathered dust in a museum drawer for a century is the oldest fossil of large plants ever found.

The find suggests we need to rethink the plant family tree. It has been estimated that land plants first emerged 515 million years ago but actual fossils are rare and not quite so old. Many botanists assume that the first land plants grew like mosses, and more complex plants like shrubs and trees evolved later.

However, the new find adds to …