Grass reproduces via seeds.
The seed contains all the genetic information needed to produce new plants.
It also has a protective coating called the testa.
The testa protects the seed from being eaten by animals.
When the seed germinates, it breaks open the testa and exposes the embryo.
The embryo then grows into a plant.
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The reproduction of grass is a fascinating process.
Grass reproduces by sending out shoots from the root system.
These shoots grow leaves at the tip and then flower.
When these flowers are fertilized, they produce seeds that can be dispersed to other plants to continue their life cycle.
This process takes place over many years until all the seedlings have grown into mature plants.
In this way, new generations of grasses will keep on growing.
Grass Seedling Development
Seedlings develop when the seed sprouts.
This happens after the seed absorbs water through its roots.
When the seed begins to absorb moisture, it starts to swell up.
As the swelling continues, the stem elongates.
Eventually, the shoot emerges from the soil.
As soon as the shoot comes out of the ground, it sends down branches that eventually form leafy structures.
Leaves appear first, followed by stems with buds.
Finally, the bud opens and produces flowers.
After flowering, the pollen grains fall onto the stigma of the female part of the flower.
Pollen grains contain male cells and female cells.
After pollination occurs, the ovary develops and releases an egg cell.
Then, the sperm enters the egg cell and fuses, forming a zygote.
A few days later, the zygote becomes a tiny ball-shaped structure known as a proembryo.
Grass Root Growth
A grass’s roots help it stay alive.
Roots provide support for the plant so that it doesn’t topple over or get buried under debris.
They also allow the plant to take nutrients from the earth’s surface.
Roots consist of two parts: primary roots and secondary roots.
Primary roots extend downward toward the soil, while secondary roots branch off from the main body of the root.
Primary roots usually start near the top of the plant, where there is more light.
Secondary roots begin closer to the bottom of the plant, where there isn’t much sunlight.
Primary roots are long and thin, whereas secondary roots are shorter and thicker.
Grass Stem Formation
Stems are made up of three different types of tissue: vascular cambium, xylem, and phloem.
Vascular cambium forms between the outer bark layers and inner wood layer.
Xylem makes up most of the center core of the stem.
Phloem surrounds the xylem and transports food throughout the plant.
The vascular cambium is responsible for producing new growth.
As a result, new tissues emerge from the cambial region.
Xylem provides strength to the stem.
It contains vessels that transport sap upward towards the leaves.
Phloem carries sugar molecules back to the roots.
The phloem consists of sieve tubes and companion cells.
Sieve tubes carry a liquid called cytoplasm. Companion cells store carbohydrates.
The formation of stems involves several stages:
- Meristems arise within the cortex.
- Meristems give rise to lateral buds.
- Lateral buds repeatedly divide to create axillary buds.
Axillary buds become inflorescences.
Inflorescence development leads to floral initiation.
To produce seeds, plants need to have sex organs.
Sex organs include stamens and pistils.
Stamens hold pollen grains on their tips.
Pistil holds the style which connects the ovaries to the rest of the reproductive system.
The ovules grow inside the ovaries.
Once fertilization takes place, they turn into seeds.
Pollen grains come in many shapes and sizes.
Some look like little balls, while others resemble pine cones.
Each grain has one large nucleus surrounded by four smaller nuclei.
The nucleus is filled with DNA.
When pollen lands on the stigma, the pollen tube grows through the style and reaches the ovule.
Inside the ovule, the pollen tube splits open, releasing its contents.
This causes the embryo sac to swell.
Eventually, the pollen tube bursts and releases another round of chromosomes.
Seeds develop after pollination.
Seeds contain endosperm and embryos.
Endosperm stores energy reserves needed during germination.
The embryo develops into a seedling.
Seedlings eventually form mature plants.
Pollinators such as bees or flies visit flowers looking for nectar or pollen.
They land on a flower and use their mouthparts to transfer pollen onto the female part of the flower.
Flowers then close so that only insects can access them.
Insects also eat pollen before it falls out of the flower.
After eating pollen, insect moves away from the flower leaving behind pollen stuck to their bodies.
When the wind blows over a field of flowering plants, some of the pollen gets carried along.
Wind-borne pollen may be deposited on other nearby plants.
If these plants happen to be male, pollen will get transferred to their pistils.
As a result, female plants will receive pollen containing genes from both males and females.
These genes combine to make offspring.
Self Pollination and Cross-Pollination
For cross-pollination to occur, there must first be contact between stamens from different plants.
Contact can occur either through direct physical contact or indirect means via insects that carry pollen from flower to flower on their bodies.
Insects carrying pollen from one plant to another area are known as vectors.
Cross-pollination occurs when two types of pollen grains mix.
One type comes from the same species, and the second type comes from a different species.
Self-pollen contains all the genetic information necessary to make viable offspring.
Non-self pollen carries foreign genes not found in the parent plant.
Therefore, it cannot contribute any new traits to the next generation.
A rhizome is a root-like structure found underground that may be either horizontal or vertical.
Rhizomes usually have thickened roots at their base called corms.
Corms store food for future growth and provide nutrients during periods of drought.
The main difference between a true root system and a rhizome is that a true root extends into the ground while a rhizome does not.
A rhizome produces shoots aboveground instead of leaves.
Some examples include horsetail, bamboo, and ginger.
If you have problems with horsetails check out our post on how to remove horsetail weeds.
Some grasses have stoloniferous roots that allow them to reproduce via horizontal growth rather than vertical shoot development.
Stolons are long root structures that extend horizontally away from the main stem.
They may be branched or unbranched.
The leaves at the top of the stolon usually die off before new plants emerge.
These dead leaves provide nutrients for developing young plants.