Challenge Me: NATURAL UNIT 4

Seeds come in various shapes . Every seed contains an embryo, or a miniature version of the plant, ready to sprout and grow when conditions are right. In addition to the embryo, seeds also contain food for the plant to begin its journey.

Some seeds, such as the lotus, can lie dormant for many years and still sprout when conditions are right. Others, like some annual grasses, must sprout within a few weeks.

Germination

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When conditions are right, the seeds germinates, which means it begins to grow. Seeds generally require water and warmth. Some seeds also require light. seed germination

Germination begins when, under the right conditions, the seed absorbs water and swells, breaking the seed coat. It then grows a tiny root called a radicle which anchors the plant and absorbs water.

Growth

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The plant then begins to develop its first proper leaves, called primary leaves. These leaves start the process of photosynthesis, or turning the energy from sunlight, water, and carbon dioxide into sugars which the plant uses for food. The plant does this by using chemicals called chloroplasts. plant growth

Reproductive Stage

In the reproductive stage of life, the plant flowers, is fertilized, and produces seeds.

Flowering

In the beginning of the reproductive stage, the plant grows a small bud. Inside the bud, a tiny flower begins to form, protected by the surrounding sepals. Eventually, the bud opens to reveal a mature flower which is the reproductive part of the plant. Flowers usually have brightly colored petals or strong scents to attract pollinators.

The male part of the flower is called the stamen, and the female part is called the pistil. Some plants have both parts in the same flower, while others have only a male or female part per flower. The stamen carries pollen on the anther, a tiny pouch, which is supported by long filaments. The pistil has three parts:

Stigma - Sticky and traps and holds pollen
Style - Tube that holds the stigma
Ovaries - Where the seeds form

Pollination

Pollination occurs when the pollen from the male anther is transported to the female stigma. Some plants can self-pollinate. Others require insects, wind, rain, birds, and other natural processes to transport the pollen.

Plants can also cross-pollinate, which means pollen from one plant is taken to another plant of the same species. This is beneficial because it creates genetic diversity, which makes the subsequent generations stronger and more adaptable. Insects like bees play an important role in pollination, pollinating plants as they collect pollen for their food.

Seeds Mature and Release

After pollination, the seeds become reproductively viable. A protective layer, called the fruit, forms around the seeds. Some fruits are large and fleshy like an apple, others are dry like the white parachute of a dandelion.

Seeds can be dispersed in diverse ways.

The simplest way is to fall to the ground. Many are eaten by birds animals and transported in their digestive tracts.
Others, like burdock, are structured to stick to passersby.
Still others, like dandelion, float easily on the wind over long distances.

The goal of all plants is to create new viable offspring through seed dispersal. Once the seed arrives at a place where it can germinate, the life cycle is ready to begin again.