Beans, Peas, and Edamame (Soybeans): The Bean Family is a Botanist’s delight, in that you can almost always figure out when a plant new to you is in this group. One reason Beans are so simple to place is that almost every plant in the family makes a characteristic kind of fruit, a single leaflike carpel termed a Legume. When plants that are not Beans make a similar fruiting structure, we call it a Follicle – but the word Legume is particular to the Bean family, and nothing else quite matches the structure. This means the Systematist and Carpologist would organize them tightly together.
Things are not so simple for the Cook. In markets, fresh Beans and Peas are often kept with the vegetables, in those slanted, wall-mounted counters where everything is misted to prevent drying. And of course, you would find shelled, dried bean seed over in dry products, near rice. But extracts and products show up almost anywhere in a market – tofu from soybeans somewhere near dairy, soy sauce with other condiments, soybean oil with other fats.
Like the major grains, different native legumes were selected by agrarian societies around the world and are associated with traditional foods of those cultures – beans in the Americas, peas in Europe, lentils in the Mediterranean, soybeans in Asia, chickpeas in the Middle East, and black-eyed peas from Africa. We understand, today, that the bean family (the Fabaceae) holds agricultural and nutritional advantage based on the family-wide capacity of their roots to partner with nitrogen-fixing bacteria. Through this association, legumes are able to take their nitrogen from thin air, which is important since proteins are nitrogen-rich. The result is that legumes provide important balance in diets around the world.