Plants inside can be great—when they’re around our minds and our bodies work well—our cognitive performance and creativity go up, we get along better with other people, our stress levels fall—the list goes on and on. To reap the most benefits from the plants in your world, make sure you include green leafy ones—cactuses and spikey plants just don’t have the psychological payoffs of Ficus plants and other gracefully curving, lushly leafed options. You only want one or two, a…