The seed of a plant is a tiny packet of life. Each seed contains a tiny plant embryo and enough protein to give the tiny plant the energy to sprout and reach through the soil. The plant embryo is not the only thing that can use the nutrition in a seed. Animals that eat seeds may also take advantage of the nutrients in the seed. For this reason, seeds are a staple in the diet of animals that range from birds and mice to humans.
All seeds have several things in common. Seeds are wrapped in a shell called a seed coating. This coating helps to protect the seed from harm. Inside the seed coating, the tiny seed embryo typically is situated on one end of the seed. The seed embryo is surrounded by a hard casing called a cotyledon. Additionally, the seed is filled with a starchy substance called endosperm. The endosperm provides food in the form of energy for the seed embryo to grow.
Seeds are divided into two classifications. These groupings are known as monocots and dicots. Monocots are seeds that do not split into two pieces. Dicots split in two. When a dicot seed sprouts, each half of the dicot becomes an embryonic leaf. These leaves are not true leaves, which develop later. Examples of a monocot include a corn kernel. A good example of a dicot seed is a bean.
Plant embryos are not the only ones who can use the endosperm in a seed. Humans who consume edible seeds can use starch, protein, vitamins and other beneficial substances found in seeds to supplement their own diet. Seeds are low in saturated fat and high in magnesium, vitamin E, phytonutrients, and poly- and monounsaturated fats, according to University of Kentucky Extension. Because seeds are plant products, they do not contain cholesterol and are naturally low in sodium.
Nuts and seeds are similar in structure. But a nut is not a seed, rather a dry fruit. Technically, this means that a nut contains a seed within it. Nuts and other fruits are adapted to be easy for consumers to eat. In this way, the seeds of fruit and nuts become easily scattered. By contrast, you have to work to consume seeds. Many seeds such as pumpkin, corn, beans or peas are buried beneath a husk, in a pod or inside a fruiting body. Seeds such as legumes or grain seed require cooking to make them edible.
If you include cereal grains, seeds account for a major portion of the human diet. Seeds may include legumes such as soy beans, green beans and peas, cereal grains such as maize, rice and wheat. Some items that are classified as nuts are actually seeds as well. These may include Brazil nuts and cashews.