A debate over plant consciousness and intelligence has raged in scientific circles for well over a century - at least since Charles Darwin observed in 1880 that stressed-out flora can't rest. Biologists believe that plants communicate with one another, fungi, and animals by releasing chemicals via their roots, branches, and leaves. Plants also send seeds that supply information, working as data packets. They even sustain weak members of their own species by providing nutrients to their peers. They also have memories, and can learn from experience. But does any of this qualify as consciousness? The answer to that question seems to depend largely on ... how humans choose to define our conceptions of the self and intelligence. We believe that our experience of life is what defines consciousness. But there is some evidence that other modes of existence are equally complex, which suggests that other living things have arguably intelligent or conscious experiences. Evolutionary ecologist Monica Gagliano insists that plants are intelligent, and she's not speaking metaphorically. "My work is not about metaphors at all," Gagliano tells Forbes. Gagliano's behavioral experiments on plants suggest that - while plants don't have a central nervous system or a brain - they behave like intelligent beings. Expanding definitions of consciousness and intelligence could mean admitting we've been limited in our worldview. What if everything around us is intelligent in its own way, and we're just not smart enough to see it?