Seed catalogs have sprung up and gardeners are thinking about their vegetable gardens and flower beds. But how do seeds take that first step from seed to seedling?
To start growing, a seed must have consistent moisture and the right temperature. It also needs oxygen to fuel the chemical processes that lead to growth.
Definition
Seeds are the way that flowering plants reproduce. They are a fertilized, mature ovule that contains an embryonic plant with food reserves surrounded by a protective coat. Seeds are the reproductive organ of gymnosperms and angiosperms (except for ferns and liverworts) and they complete fertilization in their mother plants.
They are the primary means of dispersal for many flowering plants and also serve several other vital functions such as nourishment of the embryo during early growth, a means to store energy and dormancy during unfavorable conditions. Seeds can be classified as either monocot or dicot based on the presence or absence of cotyledons, one or two leaves that form after embryonic germination.
When a seed absorbs water it reaches a stage called imbibition where enzymes are activated to break down stored compounds within the seed into smaller molecules that can be used by the embryo.
Origin
Seeds are what distinguish vascular plants from bryophytes and other plant types that lack them. They evolved from the progymnosperms, a transitional group of naked seed plants that superficially resembled conifers but reproduced like ferns.
The earliest true seeds appeared in the fossil record during the Devonian period. Three important evolutionary trends that facilitated the transition from progymnosperms to seed plants were the evolution of heterospory (female- and male-like spores), the development of integuments in ovules, and pollen receiving structures.
A seed is a small structure that contains an embryo and a supply of nutrients for the embryo to grow into a new plant under favorable conditions. The embryo grows inside the seed coat and attached to a cotyledon or seed leaf, which is called the plumule.
Function
Seeds are used to propagate many crops including cereals, legumes, forest trees and turfgrasses. They also provide most cooking oils, many beverages and spices and some important food additives.
In some seeds the embryo or endosperm dominates and provides most of the nutrients. Storage proteins in these two tissues differ in amino acid content and physical properties. The gluten of wheat, important in providing the elastic property to bread dough is a protein of the endosperm.
During dormancy the seed loses some of its DNA integrity. A protein able to repair double strand breaks is important in seed longevity and germination. In computer programming a random seed is a number that generates the same sequence of numbers over and over. It is useful in testing algorithms that depend on a random sequence of integers.
Components
Seeds are small embryonic plants enclosed in a covering (the seed coat) and with some stored food. They are the product of fertilization within the ripened ovule of gymnosperm and angiosperm plants. Seeds have an embryo, a prospective shoot, the plumule and one or more cotyledons (one in flowering plants and several in monocots).
A major part of seed is the endosperm. This bulky tissue stores nutrients for the embryo until germination. It also contains the triploid megagametophyte that carries the male gametes in seeds of dioecious plants. A new study quantifies the relative evolution of seed reserve and coat mass, revealing that desiccation-sensitive seeds allocate more to their reserves. This explains their greater success and also provides insights for designing improved seed-storage strategies.
Symbols
The Seed of Life is a symbol that represents creation. It is a powerful tool for connecting to higher frequencies and attracting positive energy. It is also associated with the number seven, which is a spiritual number that symbolizes vulnerability and wisdom.
The symbol consists of seven evenly spaced circles that form a symmetrical pattern. When added together, the shape creates a torus, which is the basic shape of magnetic fields. It is also the shape of the aura field that surrounds the human body.
Peirce referred to these two properties of a symbol as its iconic and symbolic ingredients. The iconic ingredient is based on its indexical power while the symbolic is based on its representational power. These powers are what make a symbol meaningful.
