Plant: Lifecycle of a Plant

Plants are present in almost every habitat, where there is a growth medium and presence of water. Despite being commonly observed in and around our surroundings, not many of us are bothered with life cycle of a plant. As you know, the basic parts of a flowering plant include leaves, stem, root, flower and seeds. But, can you believe that there is a specific stage for development of these plant parts? The successive growth stages are more profound in flowering plant species. Scroll down to understand all about plant life cycle for kids.

Lifecycle of a Plant: Stages Explained

When we say life cycle of a plant, it refers to the stages of growth and development in seed producing plants or angiosperms. It includes germination of seeds, maturity of the seedlings into adult plants and then, seed setting. In other plant groups, like pteridophytes and gymnosperms, the basic stages may differ slightly. Following is a detailed information pertaining to flowering plant life cycle:

Seed Dormancy: Some plant seeds have a dormancy state, wherein it remains quiescent until the arrival of favorable environmental conditions. As soon as required growth factors are provided, the dormant seeds are ready to germinate and grow. However, this seed dormancy state is absent in many flowering plants.

Germination of Seeds: Seeds land in the ground soil fail to germinate or sprout, until required temperature range, oxygen and water are available. When such growth factors are provided, the seed germination process starts. Seeds containing viable embryos break open the outer covering layer (seed coat) and sprout. Seed germination is marked by development of first root.

Growth of Seedlings: As a basic step of seed germination, the hypocotyl (upper stem) pushes the cotyledons above the soil. These are not true leaves, but they are called seed leaves. Within a few days to a week time, new leaves develop from the hypocotyl and at the same time, the stem continues to increase its height. Under the soil layer, the roots proliferate and anchor to the soil particles.

Maturity of Plants: The elongation of stem occurs in response to light (a phenomenon called photoperiodism). In contrary to this, roots penetrate down by a process called geotropism. The roots absorb water and nutrients, which are then sent to upper stem and foliage. Green leaves manufacture food by means of photosynthesis. These collective processes lead to development of adult plants.

The Flowering Stage: In the plant life cycle, the stage that leads maturity is development of flower buds, which later open into full blooms. Each complete flower possesses male reproductive organs (stamen) and female reproductive organs (pistil). Besides these essential parts, sepals and petals are also present. These different parts of a flower are responsible for fertilization process.

The Pollination Stage: The key process responsible for fertilization is pollination, meaning transfer of pollens to the receptive part of the female reproductive organ. As soon as pollens mature, they are carried to the stigma with the help of pollination agents (wind, water, insects, birds, etc.). Depending upon the plant species, self pollination or cross-pollination takes place.

Double Fertilization Process: The final stage in the life cycle of a flowering plant is double fertilization. For this to take place, the pollen grain lands on the accessible stigma and absorbs moisture and germinates, forming a pollen tube. It then passes through style and reaches the ovary. From the pollen tube, two male gametes (sperms) are released, one of them fuses with the egg forming a viable zygote and the remaining combines with two polar nuclei of the embryo sac to form endosperm. The zygote then develops into embryo, which is surrounded by endosperm.

In case of potato, the life cycle starts from seeds or tubers. For the latter type, you might have noticed sprouting potatoes in your storage area. In such a case, the tuber itself provides essential nutrients required for the initial growth of potatoes. Retain the spouts along with the tuber in the same place and you can demonstrate photoperiodism of plants. The stems will orient themselves in response to availability of light. Following this, flowers will develop and seed setting takes place after pollination.

This was a simplified information about plant life cycle. In biology, the life cycle of a plant determines how long a particular plant species survives. Say for example; a seasonal plant flowers and sets seeds within a particular season, while an annual flowering plant completes its life cycle in one year. Likewise, biennial plants require two growing seasons for completion of its life cycle.