A seed is a small, usually flat, embryo that begins the life of a new plant. In most plants, seeds have a protective coat and some food stored inside.
A seed is an important part of many plant species, including trees and some grasses. These plants rely on seeds as a source of food and fuel.
Functions
A seed is a part of a plant which can grow into a new plant. It contains an embryo (a miniature plant), a food reservoir called endosperm, and a protective seed coat.
Most seeds are products of sexual reproduction, which produces a remixing of genetic material and phenotype variability that is controlled by natural selection. Seeds also serve other important functions such as nourishment of the embryo, dispersal to a new location, and dormancy during unfavorable conditions.
The functions of seed differ among plants and even within a single species. Some plants use water-dependent means of propagation, such as spores, while others have evolved a multicellular structure that allows them to disperse by wind, insects, or other animals.
Origin
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. The seed coat protects the embryo from physical and mechanical damage.
In flowering plants, a seed contains an endosperm which is used to store nutrients (starch) to allow the rapid growth of the embryo. The endosperm also has oil, which the plant uses for lubrication and as a source of energy.
A seed consists of three basic parts, the seed coat, the endosperm and the embryo. The seed coat is used to protect the seed from physical, mechanical and temperature-related damage.
Structure
A seed is the characteristic reproductive body of gymnosperms (conifers) and angiosperms (flowering plants). Both groups undergo fertilization, which results in the fusion between an egg cell and a sperm nucleus to form an embryo.
The resulting embryo is enclosed in a structure called the seed coat. This protects the embryo from damage.
Most seeds also have a supply of stored food materials known as endosperm. The endosperm is a rich source of carbohydrates, proteins and fats and supplies energy for development.
The shape of the seed can vary, and is usually determined by its environment and the plant species from which it comes. Typically, seeds are bean-shaped (reniform), ellipsoid, or globose.
Dispersal
Seed dispersal is an adaptive mechanism that allows plants to reproduce, expanding their geographic range and population size. It can be done through a variety of means, such as wind dispersal (also known as allochory) or animal-mediated dispersal.
The evolution of dispersal strategies is a complex process. It requires a combination of selective pressures, knowledge of dispersal mechanisms and environmental conditions.
Anemochory, or wind dispersal, is one of the earliest ways for seeds to spread. Some plants, such as water lilies and palm trees, have fruits that float on the breeze and can disperse long distances.
Many animals can help with the movement of seed by depositing them on their fur or plumage. They can also use their specialized senses, which include smell and taste, to find fruiting plants and eat them.
