The 5 Stages of Plant Reproduction

Germination

Germination is the process by which a seed sprouts and grows into a new plant. All seeds have an outer coating called the seed coat, which prevents water from entering the seed, protecting it from dehydration. For a seed to sprout and grow, the seed coat must be broken. This can be accomplished in several ways:

- Mechanical damage to the seed coat (with a garden spade, for example, or by passing through the digestive system of an animal). Some seeds are dispersed by being eaten by an animal, passing through its digestive system, and being excreted; the seed is then deposited far away from the parent plant.

- Exposure to warm, moist conditions, which soften the seed coat so that water can enter - Exposure to chemicals that break down the seed coat. One example is the use of chemicals to control weeds in fields of crops.

Growth

Once germination has occurred, the plant must grow and develop so that it is large enough to flower and produce seeds. This process occurs in a series of stages and is called a plant’s life cycle. The first stage of the life cycle begins with seed germination and ends with the seedling becoming established (when the roots have grown long enough to reach the soil below and the young plant has produced its first leaves). During this time, the plant takes in water from the soil, and nutrients from the water are used to build new cells. Through photosynthesis, the plant also takes carbon dioxide from the atmosphere and makes its food (sugar) as well as oxygen. As the plant grows and produces new leaves, stems, and flowers, these new parts take in nutrients and water from the soil, and the plant uses the nutrients to grow. The rate of growth depends on the plant species, environmental conditions such as temperature and sunlight exposure, and the amount of water and nutrients available.

Reproduction

After the seedling has grown tall enough to produce flowers, the plant enters the reproductive stage of its life cycle. During this stage, plants produce flowers containing both male and female reproductive structures. Flowers also serve as a way to attract pollinators, such as insects and birds, to the plant so they can help with pollination. A flower has three main parts: the sepals (collectively called the calyx), the petals (collectively called the corolla), and the stamens (male) and pistils (female). The sepals and petals of the flower are usually green and serve to protect the flower and attract pollinators. The stamens produce pollen, which is a grain-like substance containing the plant's male reproductive cells. The pistils are female reproductive structures that produce seeds when pollinated.

Pollination

Pollination is the transfer of pollen from the stamen of one flower to the pistil of another flower, or from a flower to the stigma of the same flower. This fertilizes the flower and causes it to produce seeds. Although plants that are pollinated by wind are also considered self-pollinating, the term “self-pollination” is used only to describe plants pollinated by pollen moved with the help of insects or birds. Wind pollination occurs when the plant's wind-borne pollen accidentally lands on the stigma of a flower on the same plant. Because the timing of flower production is not synchronized among different plants, most plants rely on other agents, such as insects and birds, to move their pollen from one plant to another. This process is known as pollination. The flower pollen is transferred to the insect while it is feeding on the flower nectar. The pollen is transferred to the next flower when the insect flies away. The insect serves as a pollinator because it moves pollen between flowers of the same plant species. The insect carries the pollen on its body, legs, or wings and then transfers it to the next flower visited. Plants pollinated by insects must be in an open area so that the insects can get to them.

Seed spreading

The final stage of a plant's life cycle is seed spreading, which occurs when the flowers die and the seeds are dispersed from the parent plant. This can happen in many ways:

- Some plants drop their seeds as soon as they ripen, so the seeds fall to the ground and germinate nearby.

- Some plants have fleshy fruits that are eaten by animals, who then scatter the seeds as they move from place to place.

- Some plants have pods that explode when dry, scattering the seeds.

Summary

Plants have developed intricate strategies for surviving and reproducing. Many plant species are annuals, which survive for only one year. During the long days of summer, plants grow and produce lots of seeds. They then die when the days grow shorter and temperatures drop. The seeds remain dormant through the cold winter months and then germinate in the spring when the weather warms. Many perennial plants grow and die each year, but they also have deep roots that survive year after year. These roots store nutrients in the soil, and the plants regrow each spring after they are cut back by cold weather. Because plants are rooted in one place and cannot move, they must defend themselves against predators and access sufficient resources such as water, sunlight, and nutrients. Plants have developed a variety of strategies for doing this, including growing tall and dense, producing spines, acquiring toxins, and producing chemicals such as caffeine and nicotine to repel herbivores and attract pollinators.