Leaves of plants are one of the most commonly used foods. We might think of lettuce, spinach and herbs such as basil and rosemary as having leaves that we eat, but there are many others. Nasturtium leaves add a peppery taste to salads. A tropical hibiscus is relished for its edible leaves. Sweet potato leaves and stem tips are common fare in some parts of the world. Other root vegetables such as turnips also offer us leaves that we can eat either raw or cooked.
Many root vegetables exist. Beets, carrots, turnips, potatoes, onions and radishes are a small sampling of common root vegetables. Other root crops such as rutabagas and parsnips are less commonly eaten in many parts of the United States. For roots to grow into strong, straight vegetables, they need a sandy or loamy soil with few rocks. Root crops can rot if they sit in water, so if you're growing a few carrots, let the soil dry out a bit in between waterings.
Stems and Shoots
We're all familiar with celery, which is a crunchy, nutritious leaf stem. Less commonly eaten stems include kohlrabi, fern fiddleheads and rhubarb. Bamboo shoots are the young bamboo plant when it first emerges from the soil---they are a delicacy in many Asian dishes. Asparagus can be called either a shoot or a stem. Even artichokes and broccoli have edible stems below their flowers, which are what we normally eat. Branches are not usually edible, but some people eat the prickly pear cactus with its nopales, or edible branches.
We probably eat more flowers than we realize. Broccoli and cauliflower are the young flowering parts of those plants, and the artichoke is the edible flower of a thistle family plant. Many flowers are used in restaurants for garnish and color. Edible flowers include many of the herbs, such as basil and calendula. Others are guava, fuchsia, daylily, Johnny jump-up and pansy, lavender, marigold, mint and nasturtium. The list is long, but be cautious; not all flowers are edible, and some can be bad for you.
When we think of eating seeds, perhaps sunflower seeds come to mind. But we eat many other seeds in the form of peas and beans, such as snap peas and lima beans. Wheat, which is what flour is made from, is a seed. And even the coffee bean is a seed---if you grow coffee plants and don't pick all the ripe, red berries that contain the seed, you'll soon see young coffee plants sprouting around the parent plant. And what would Mexican food be without refried beans? They are simply pinto beans that have been cooked, mashed and fried.