Understanding the distinction between a nut and a legume can be a subtle yet important aspect of botany and nutrition. While both may seem similar as they are encased in a shell, their differences are rooted in botanical structure and family classification. Nuts typically contain a single seed that is not attached to the shell and can belong to various plant families. In contrast, legumes are characterized by multiple seeds that are often affixed to the pod's inner wall and are exclusively part of the Fabaceae family, which encompasses about 20,000 species. This distinction is crucial for those interested in plant biology, agriculture, or dietary choices, as it influences the nutritional profile and culinary uses of each group. By delving into the specifics of nut vs legume, one can make informed decisions that align with their dietary needs and preferences.
Nuts in Botany
In the strict botanical use of the term, a nut usually has only one seed, or two at most. Additionally, a true nut is always "indehiscent," meaning it does not open on its own. The seed of a true nut is never attached to the ovary wall, but instead is loose or fitted into the nut pod. All of these traits can be seen in chestnuts, hazelnuts, and similar nuts.
Botanical Categorization of Legumes
The major element that sets legumes apart from nuts is that they are from one particular family of plants, called either the fabaceae or leguminosae family. They also frequently contain multiple seeds; it is not uncommon for a pea pod, for example, to contain half a dozen peas. The majority of legumes are "dehiscent," opening naturally along a seam on two sides; again, the pea pod is an obvious example of this. They often contain seeds that are attached to their pods, rather than simply fitting within them. Legumes are also known for having fruit that is high in protein, and they can replenish nitrogen in soil, making legumes ideal for use in crop rotations.
Confusion Over Peanuts
Looking only at these common distinctions, it can be difficult to determine whether a peanut is a legume or a nut; it contains two seeds, the pod is indehiscent, and the seed is not attached to the ovary wall. Despite its name, a peanut is a legume and not a nut. This is why some people who have allergies to certain nuts can still eat peanuts, and other individuals with peanut allergies can eat true nuts.
Culinary Distinctions
It is important to note, however, that in cooking, the botanical definition of a nut is less important than its culinary definition. In culinary terms, a nut is often considered to be any large seed used in food, which comes from a hard shell. Peanuts certainly fit this description, and chefs often use them in much the same way as botanical nuts. The difference between nuts and legumes is much less important in a kitchen, as long as they are used well within a dish.
