A leaf is filled with chambers illuminated by gathered light. In these glowing rooms photons bump around and the leaf captures their energy, turning it into the sugar from which plants, animals, and civilizations are built.
Chloroplasts, fed by sun, water, carbon dioxide, and nutrients, do the leaf’s work. They evolved about 1.6 billion years ago when one cell, incapable of using the sun’s energy, engulfed another cell – a cyanobacterium – that could. That cyanobacterium became the ancestor of every living chloroplast. Without their chloroplasts plants would be left like the rest of us, to eat what they find. Instead they hold out their green palms and catch light. If there is magic in the world, surely this is it: the descendants of tiny creatures in leaves, capable of ingesting the sun. [Rob Dunn writing in National Geographic]