Many people commonly use the terms “nut” and “seed” interchangeably, often referring to any hard-shelled, edible plant part. Botanically, however, these terms represent distinct structures with different origins and functions within the plant kingdom. Understanding their precise definitions clarifies why many familiar foods are often miscategorized. This distinction highlights the intricate ways plants reproduce and develop.
Understanding Seeds
A seed is botanically defined as an embryonic plant enclosed in a protective outer covering, known as a seed coat. It contains stored food reserves, such as endosperm, which nourish the embryo during germination. Seeds form from the ripened ovule after fertilization, serving as the fundamental unit of reproduction for flowering plants and conifers. Common examples of botanical seeds include beans, corn kernels, sunflower seeds, and the “pits” found inside fruits like peaches.
Understanding Nuts
A true nut, in botanical terms, is a specific type of fruit. It is a simple, dry fruit that typically contains a single seed. Its defining characteristic is a hard, woody pericarp, or fruit wall, which does not naturally split open at maturity to release the enclosed seed. This indehiscent nature means the seed remains protected within its tough shell. Examples of true botanical nuts include acorns, hazelnuts, and chestnuts.
Botanical Differences
The primary distinction between a nut and a seed lies in their botanical classification and structural origin. A seed is an undeveloped plant with stored food, originating from a fertilized ovule, and its main purpose is plant propagation.
Conversely, a true nut is a type of fruit, a mature ovary that houses the seed within its hard casing. The nut’s hard shell provides protection for the single enclosed seed. Seeds, when mature, are often dispersed from their parent plant and are ready to germinate, while the entire nut, as a fruit, is dispersed. This difference in origin means that while all nuts contain a seed, not all seeds are contained within a botanical nut.
Common Culinary Confusions
The common understanding of “nuts” often diverges from botanical classifications, leading to culinary confusions. Many items called nuts in daily life are not true botanical nuts. This discrepancy arises because culinary terms often group edible, fatty kernels with hard shells, regardless of scientific origin.
Peanuts, for instance, are botanically legumes, and grow underground in pods containing multiple seeds. Almonds, walnuts, pecans, and pistachios are seeds found inside a fleshy fruit called a drupe. A drupe features an outer fleshy layer surrounding a hard inner shell, or “stone,” which encases the edible seed. Unlike fruits like peaches or cherries, where the fleshy part is consumed, with these “culinary nuts” we discard the outer fruit and eat the seed from within the stone. Brazil nuts and cashews are also botanical seeds; cashews are specifically classified as drupe seeds that grow externally to a cashew apple.