Plant power
Take a breath, and give thanks to photosynthesizing bacteria. Look at the trees, grasses, birds, and squirrels and think of the early plants, which paved the way for the life around us. “Plants have a wonderful way of reminding us how lucky we are to be here, how lucky we are to sit on 3.5 billion years of evolutionary history and be here to have this conversation,” William Friedman, director of the Arnold Arboretum, said Monday during a talk at the Hunnewell Building. The world we live in was produced by many evolutionary steps, and some of those steps have been taken many times by different organisms. Arborescence — changes in plants that create towering trees — evolved five times over 20 million years, for example. But there were two important changes that have occurred only once in the evolutionary record, and we have the precursors of plants to thank for both,...