Plants: Annual Rings and Roots

Why are plants different?

Many plants grow very high, but others remain small. Deciduous trees shed their leaves in autumn, but only a few conifers shed their needles. The roots of some trees grow very deep in the ground, but others remain near the surface. A few species even live in a mutually beneficial and interdependent relationship called symbiosis. Everything a plant does is for its survival so all the differences seen in plants are adaptations made depending on its environment. The plant species continues to live even after a plant dies, since it always reproduces before dying.

How are annual rings formed in trees?

When trees grow, they accumulate wooden fibres around their heartwood. These fibres are bright and porous in spring so that a lot of water can reach the fresh leaves through them. By autumn, they become darker and thicker so the tree becomes stable and resistant to frost in the winter rest period. This process forms a bright ring and a dark ring around the heartwood every year. If you count the dark rings of a horizontal cross section of the tree trunk, you can find out the age of the tree. In the tropics, where there are no distinct seasons, the trees do not develop any rings. They grow all round the year and do not have any rest period.

How do roots help plants?

Roots absorb water and the dissolved nutrient salts from the soil. They also store the nutrients as a reserve that the plant can survive on, when the soil dries up. The roots also anchor the plant firmly in the soil to safeguard against uprooting due to wind and bad weather. Roots change shape and adapt depending on their environment. Shallow-rooted plants, uch as spruces, can hold their ground even at places where the soil cover is very thin. Plants such as pine trees, whose tap root grows deep in the ground, are found at places where water is available at great depths inside the earth.

The Author of this article, Arun Mohan is writing articles for Swap Dial and Agrraj Consultancy Services