The Plants Kingdom – Algae

Algae are the simplest kinds of plants. They contain chlorophyll; therefore, they can make their food by photosynthesis. They lack vascular bundles, i.e. they do not posses xylem and phloem. Their thallus lacks true roots, shoots and leaves algae include unicellular plants to very big multicellular plants. They do not form embryo after sexual reproduction. Commonly, algae are colored and they can grow up to 40 or 60 meters in length.

            Most algae grow in rivers, ponds, lakes and oceans. Some can live in moist places on land, mountains and near trees. A few species of algae are found on the ice in the Polar Regions and in hot water springs. Some of the blue- green algae can survive even at 70-80 degree centigrade. Some algae grow on plants and a few complete their life cycle inside some plants. Many algae are saprophytic and parasitic. The best known algae are probably the seaweed found at beaches.

            About 25-30 species of algae are used as food by man. The algae porphyra of phiopcae class is a common meal in Japan. In china, Nostoc commune is used as food. In India, algae are used to prepare ice-cream, chocolate milk, gelatin and beer. Some algae are poisonous in nature and can paralyze a person.

            We get carbohydrate, vitamins A, B, C, D, E and other materials from algae. Fish depend on algae for their food. Many algae obtained from oceans are rich sources of iodine, potassium and other minerals. Algae are a good fertilizer also. The red algae grow in large colonies and turn the water red. Some red algae also form islands.

Different species of algae

Leaves Green in Color

Why are leaves green in color?

            Leaves come in various color but most often they are green. Do you know why the leaves of almost all plants are found in this color?

            We know that the color of any substance depends upon its property of absorption and reflection of the different colors of light. The leaves of the plant appear colored due to the presence of some specific substances in them. For example, the presence of chlorophyll makes them appear green while the presence of carotene makes them yellow.

 Chlorophyll gives the leaves their green colour

            When the leaf contains more than one substance, the color is a mixture. The leaves, which contain both chlorophyll and carotene, appear yellowish green.

            New leaves of some plants contain a red substance called anthocyanin, which gives the pink or red color to the tender leaves. With the passage of time, chlorophyll and carotene are formed in these leaves, which ultimately turn them green.

            The structure of chlorophyll molecules is such that when the sunlight (mixture of seven colors) falls on them, they reflect the green color and absorb the rest. It is this green light that is visible and makes the leaf green.

            Plants synthesize their food with the help of chlorophyll in the presence of the sunlight, carbon dioxide and water. This process is called photosynthesis. Plants without chlorophyll like fungi cannot make their own food. They depend on other living beings. Such plants are called parasites.

            So, you see chlorophyll is very important substance for plants. Apart from imparting the green color to them, chlorophyll also helps a plant to synthesis’ food.