We sometimes take things for granted in life. What is within a seed is one of those things for most gardeners. We plant the seeds there or in a seed-starting medium & wait (sometimes anxiously) for the sprouting to begin. Yet knowing the structure of the seed is the first step in completely comprehending the germination process.
A Seed’s Anatomy
Seeds are quite clever machines when we stop to think about them because they can regulate when they emerge from the ground. When certain requirements for temperature, moisture, oxygen, and light are fulfilled, this change from seed to seedling occurs for most plant species. Let us first examine the components of seed to better comprehend the germination process:
- Seed coat – The seed coat is the first part of a seed. This seed coat, either thin and soft or thick and strong, shields the embryo from damage and dehydration.
- Embryo – The embryo is concealed inside the seed coat. The embryo is like a miniature plant with leaves, a stem, and a root.
- Endosperm – The endosperm is the third component of the seed. A feeding supply for the seedling is present in this tissue. This gives the sprouting seedling the energy it needs to develop until it can start photosynthesizing its food.
What Else is Inside Seeds?
The anatomy of the seed is made up of the seed coat, embryo, and endosperm. However, it does not fully convey the tale. The result of sexual reproduction is the seed. As a result, it carries both its mother’s and father’s DNA. Since the pollen or the ovule come from the same plant, self-fertile species have almost identical copies of DNA.
The father and maternal DNA originated from different plants in a cross-pollination scenario. Plant breeders may create hybrid varieties by cross-pollinating two or more unrelated but related plants. Several plant species are polyploid or contain more than one pair of homologous chromosomes.
The cells of the embryo house the chromosomes. The following components of the seed structure are also present in the embryo:
- Cotyledons — During germination, these embryotic leaves are the first to emerge. Plant species are classified as monocots when they only have one cotyledon, like grass. Dicots are plants having two cotyledons.
- Hypocotyl — The hypocotyl is where the cotyledons and the embryo’s radicle or root converge. The hypocotyl is in charge of raising the developing tip and, in many plant species, the seed coat holding the cotyledons above ground once the root emerges from the seed.
- Plumule — This crucial component of the seed embryo will grow into the plant’s branches. The plumule will produce the first genuine leaves.
- Mycropyle — The mycropyle, a tiny aperture in the seed coat, enables the exchange of gas and water. Water and oxygen are necessary for many plant species to germinate.
- Radicle — The radicle or root, which resembles a little tail on plants like peas, is the first portion of the embryo to break through the seed coat during germination.
What Causes Seeds to Grow?
As you can see, a seed’s structure affects how well it germinates. We anticipate the following outcomes when we plant the seed:
- Imbibition — Water is absorbed via the mycropyle if optimal germination conditions are satisfied.
- Translocation and digestion — Enzymes within the seed are activated by water. These enzymes are responsible for dissolving food in storage and making it accessible to the embryo.
- Germination — The radicle protrudes from the seed coat as the embryo starts to develop. For the cotyledons to separate from the seed coat, the hypocotyl forced the seed coat carrying the cotelydons up through the soil line.
The seedling’s growth continues from this point forward. Soon after the plumule develops, we will have a plant fit for generating food, embellishing our houses, or enhancing our surroundings.