Botany : An Introduction to Plant Biology,

If you look around right now, chances are you’ll see a plant. It could be a succulent in a pot on your desk, grasses or shrubs just outside your door, or trees in a park across the way. Proximity to plants tends to make us happy, even if we don’t notice, offering unique pleasures and satisfactions. And of course without plants, we wouldn’t even be here: Not only do plants produce oxygen, they also produce their own food—the food that directly or indirectly supports us and all animal life on the planet.