Seed is a mature ovule comprising an embryo or miniature undeveloped plant and food reserves enclosed in a protective seed coat. It is the principal means of reproduction for flowering plants (angiosperms) but not for ferns and liverworts that use water-dependent methods.
Test different dispersal mechanisms by dropping a plain “seed” and a seed with an interesting design in front of a fan to see how far they travel.
Definition
In sports, a seed is the preliminary ranking of a player or team in a tournament. It’s designed so that better teams face weaker ones early in the playoffs and have a chance to advance to the final round. It was first used in tennis and has since spread to other sports, including American football, ice hockey, and basketball.
In botany, a seed is an embryonic plant enclosed in a protective covering called a seed coat and contains some stored food material. Seeds form when the ovule in flowering plants (angiosperms) is fertilized by sperm from pollen, forming a zygote. The zygote develops into a seed through a process called germination.
There are several different types of seeds, including heirloom, certified, and breeder seeds. Heirloom seeds are traditional varieties of plants that have been passed down through generations, while certified and breeder seeds are created by plant breeders and are typically purebred. They are usually labeled with a color that indicates the type of seed, such as blue for certified seeds, white for foundation seeds, and yellow for breeder seeds.
Origin
Seed plants first evolved during the Devonian era. Fossils of ferns and seed-like structures called progymnosperms are found in Paleozoic rocks, but their evolution into gymnosperms is a mystery. One theory relates to the development of structures called cupules, which are a group of sterile spores that fuse to form an integument. Progymnosperms were paraphytic, and spores were dispersed by wind.
The evolution of seeds led to a remarkable diversity in their size, shape, and dispersal mechanisms. Some seeds have fleshy appendages to entice animal dispersers; others have hooks, barbs, or sticky hairs to attach to fur or feathers; and some have wings for wind dispersal.
Most seeds are enclosed in a protective structure called the seed coat, which contains an embryo and food storage tissue called cotyledons. Some seeds, such as those of monocots (such as grasses) and some dicots that are not endospermic, do not have the embryo in their seed; these are referred to as exalbuminous seeds.
Functions
Seeds provide a number of essential functions, including multiplication, perennation (surviving seasons of unfavorable conditions), dormancy, and dispersal. They are also critical to plant adaptations, as they enable plants to fill terrestrial niches that would otherwise be unavailable.
Seed consists of a miniature, undeveloped, haploid embryo, stored food for its early development after germination, and a protective coat. The nutrient supply within the seed is provided by a type of starch or protein stored in the endosperm.
During germination, the embryo develops into a new plant with an upward growing shoot (the plumule or epicotyl) and a root called a radicle. The cotyledons, one or two in flowering plants, and several in Pinus and other gymnosperms, provide the embryo with nourishment as it grows. The seed coat protects the embryo during dormancy and inclement weather and helps the seed to withstand natural dispersal mechanisms such as wind or water. The activity of DNA repair enzymes, such as poly ADP ribose polymerases, is necessary to maintain seed viability during storage and dormancy.
Diversity
Seeds are an important part of the diverse world of plants. They can be used for food, in plant breeding to produce new varieties with desirable characteristics, and in landscaping. They are also a rich source of biodiversity, from the stories of women who hid heirloom African rice varieties in their hair as they were being transported aboard slave ships to farmers in Arizona who recently revived a corn variety their ancestors grew and ate for generations.
Despite their importance, seeds are relatively little studied, with most studies carried out on a single model species, Arabidopsis thaliana. Cecilia’s work will change this by allowing researchers to understand how genes regulate the development of the ovule and seed in a wider diversity of plants. This is critical, as global climate changes threaten crop biodiversity. Our research will also enable more accurate predictions of how plant diversity is affected by global changes in the density and distribution of soil seed banks.
