Seed is the characteristic reproductive organ of flowering plants and of gymnosperms (conifers, cycads). It is a mature ovule containing an embryonic plant with stored food and enclosed in a protective outer covering.
Seeds give a seedling a much faster start than spores. They usually have larger food reserves than spores.
Origin
Seed (from the Latin samen) is the characteristic reproductive body of flowering plants and gymnosperms, consisting of an embryo or miniature undeveloped plant plus food reserves enclosed within a protective coat or coats. Seeds are ideally adapted for many functions, which may not always be directly related: multiplication, perennation (surviving periods of stress such as winter), dormancy and dispersal.
Cecilia and her team are beginning to understand one of the complex gene networks that govern ovule and seed evolution. They are investigating genes affecting the formation of seed-related structures, notably integuments and embryo sacs.
Seeds are the most common way that a plant reproduces, and it is possible to grow a new plant from any seed. If seeds are open pollinated, they will produce the same type of plant as the parent plant. This is called growing true to seed. Seeds are also used in the manufacture of medicine, such as castor oil and the quack cancer drug laetrile.
Functions
Seeds protect and nourish a plant embryo and carry food that supports it as it begins to grow. They also function as a means of reproduction, remixing genetic material and introducing new phenotype variability to the parent species.
They are the source of many important plants and foods including cereals, legumes, nuts, vegetable oils and spices. They are dispersed by birds, mammals, reptiles and fish that consume them and sometimes carry them to new locations where they germinate and grow into seedlings that produce more seeds.
The seed’s ability to withstand environmental conditions and start growing is dependent on the interactions of its three main components: the embryo, the endosperm and the seed coat. The embryo is protected by the outer seed coat, which has different protein-based structures that vary between dicot and monocot seeds. The nutrient supply to the embryo and endosperm is controlled by specialized tissues in the seed coat that direct a flow of assimilates from the vascular system of the mother plant.
Parts
Seeds are a structure that contains the embryo of a flowering plant. When grown under favorable conditions, seeds develop into a full-grown plant. Seeds are found in a variety of shapes, sizes, and colors.
The seed coat is a protective covering that is hard, thick and brown in color. It is made from the outer layer of the ovule, called the integument. It contains two layers; the outer layer is known as testa and the inner one is called tegmen.
During germination, some parts of the embryo break out of the seed coat. These parts grow downward and become the rudimentary roots, while other parts grow upward and become the stem and leaves. The radicle is a small embryonic root while the cotyledons are specialized seed leaves.
The cotyledons store food in the form of starch and proteins. This stored food provides nourishment to the embryo during seed germination. The embryo is fertilized by sperm and becomes the seedling of the new plant.
Varieties
A variety of a kind of seed has a different set of characteristics from other varieties of that same kind. A variety name is the legal term used to identify a particular kind of seed, and a person who maintains a particular variety can be legally called a “maintainer” for it.
Only pedigreed seed that has been grown, sampled, tested, and graded according to regulations can be labelled, advertised, or sold with a variety name. Seeds that have been genetically modified are referred to as GMO.
Master Gardener volunteers across Minnesota test vegetable and flower varieties each year in their home gardens, seeking out varieties with exceptional taste, productivity, ease of growing, space savings and other qualities. The top performers are referred to as Minnesota Winners and are often available from local retailers or online. Other seed types include open-pollinated, hybrid and heirloom. Seeds of all these types are needed to help sustain agriculture and bring the joy of gardening to more people.
