Seed is the fertilized ovule of flowering plants and gymnosperms, containing an embryonic plant with a store of food reserves, wrapped in a protective coat. Seeds germinate and grow into adult plants when environmental conditions are favorable for them.
Johnny’s Selected Seeds is a large, employee-owned company that carries hybrid, open pollinated and heirloom seeds for vegetable, medicinal and culinary herbs and flowers. They also sell gardening tools, equipment and supplies.
Embryonic stage of a plant
The embryonic stage of a plant, also called plant embryogenesis, is the process of development from zygote to seedling. This stage includes cell growth, and the storage of macromolecules as food and energy sources for germination and seedling growth. This is a critical phase for the success of the seed as a new organism.
Following fertilization, the zygote elongates and divides asymmetrically to produce an apical cell resting above a basal cell that produces the suspensor. Oriented divisions in the apical cell define zones that will form the tissues of the principal organ systems.
In angiosperms, radial patterning is established in the globular embryo, and the axial body plan is evident at the heart stage. This is a complex process that involves proliferation, morphogenesis, and organogenesis. Cecilia’s research is aimed at understanding one of the gene networks that regulates ovule and seed development, and how this network has evolved over time. Her work will allow scientists to study the molecular evolution of a key step in seed development, and shed light on the evolutionary divergence of plants.
Shape
The shape of a seed is an important characteristic that affects the way a plant germinates. It can be shaped like a sphere, oval, or heart and is the result of various biological processes. The shape of a seed can also be used to distinguish between different varieties or species. It is an important tool in seed taxonomy.
Several models have been developed to describe and quantify seed shape. These include the cardioid, ellipse, and the contour of Fibonacci’s spiral. In addition, a number of morpho-colorimetric techniques can be used to characterize seeds and fruits.
The main characteristics of a seed are its root part, or radicle; its prospective shoot (plumule or epicotyl); and one or more cotyledons. The cotyledons are the embryonal tissues that support the growing parts of the seed. They are located in the endosperm and are pressed tightly against it. They contain a small embryo and storage tissue. A seed can have a single monocotyledon or two in dicotyledons and more than two in gymnosperms.
Dispersal
Seed dispersal allows a plant to grow away from its parent and occupy new habitats. It also increases genetic mixing in a population, which is essential for evolution to occur. Seeds that are not dispersed will often remain dormant in soil, accumulating and losing their nutrients over time.
Many plants, including trees, enclose their seeds inside fleshy, edible fruits that attract hungry animals. Animals that eat fruit, known as frugivores, ingest the seeds and process them in their digestive tracts before regurgitating or depositing them elsewhere. This is known as endozoochory.
Some seeds travel far distances on the wind, such as dandelion seeds or the fluffy helix of maple tree seeds. Others float away, such as those of orchid plants, wood cranesbill, and witch hazel. And yet others explode, like the hexaploid seeds of Himalayan balsam and squirting cucumber. The link between animal behavior and seed dispersal has important demographic and evolutionary implications for plant populations. Loss of dispersal may be a key driver in forest loss and degradation, climate change, habitat fragmentation, and invasion by alien species.
