As denizens of planet earth, we keep looking for intimate companions on our journeys through space and time. Gods, aliens, or chimps dressed in tuxedos—we outfit them with traits and feelings that resemble our own. Every once in a while a book comes along that even assures us there are close emotional and spiritual relationships between plants and humans (for example, 1973’s The Secret Life of Plants). Another book of the same era argued that playing soft, gentle music to plants enhanced their growth while hard rock created botanical monsters.Scientists naturally cringe at such experimentally deficient nonsense. But we share much DNA with plants, and valid comparisons across the taxonomic kingdoms may work to the benefit of each. Daniel Chamovitz, in his new book What a Plant Knows: A Field Guide to the Senses, seeks to define the barriers and bridges between us. Chamovitz, a biologist and director of the Manna Center for Plant Biosciences at Tel Aviv University in Israel, shows...