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  • How many plant species are there?

    How many plant species are there?

    Today, scientists are aware of around 320,000-500,000 different species of plants, but they estimate this number to be much higher. Many of the known trees and flowers come from Asia, while other species of plants thrive in the tropical rain forests. Some plants have adapted to live in or below water, whereas some have adapted to live in the desert areas. Algae, lichen, and moss also belong to the plant kingdom.


    How do we differentiate between plant species?

    Earlier the scientists differentiated between plants mainly by their appearance. Today, plants are classified according to their evolution, i.e., on the basis that all members of a group must have shared a common ancestor more recently than they have with any species outside the group. Thus, the plants are broadly classified as those containing chlorophyll (the green plants) and those without chlorophyll. The green plants include the green algae and the land plants, which grow towards light against the Earth's gravity. The land plants include the mosses, the vascular plants such as ferns and horsetails, and the seed plants. These also include the conifers (gymnosperms) and the flowering plants (angiosperms).




    Water pipe on plant species


    You need: Two glasses of water, a knife, a flower with white blooms (such as carnation), red or blue ink
    Do as follows:Split the stalk of the flower lengthwise. Put the ink in one of the glasses. Push both the glasses together and place half of the stalk in one glass and the other half in the other glass. Wait for 1-2 hours.


    shrubs

    What is the difference between trees and shrubs?

    The main difference between trees and shrubs is their size. Trees are much taller than shrubs and their root balls (system of roots with attached soil that supports the health of the tree) are also bigger. Unlike the thin and flexible stalks or stems of the shrubs, trees have thick stems to bear the load of the heavier and bigger leaves, branches, and fruits. Since trees are taller, they need to transport water from the soil much further up than the shrubs. This is done by several thin hair-like pipes in the stem and the branches.


    in botanical gardens, we find domestic plants as well as those from rain forests.

    Many lichens grow in inhospitable terrain; for instance, in the rocky highlands and cold Arctic. They also grow on the walls of the houses in big cities. The growth rate of lichens is very slow-a few species grow less than one millimetre in year. If you step on them, you may destroy in seconds a plant that took hundreds of s of years to grow. Since lichens are very sensitive to air pollution, they are often used as pollution indicators. The cleaner the air the more lichen will grow.


    greenalgae

    Green algae like these are often washed ashore from the sea when there is a flood. Some species are very tasty and are served as a delicacy in some countries.

    Bacteria are single-cell organisms without the cell nucleus. Viruses are only nucleic acid molecules in a protein coat. They belong neither to the animals, which are multicellular organisms, nor to the plants, which always have a cell nucleus. While most viruses make humans, animals, and plants sick, many bacteria are good for humans. For example, bacteria in the gastrointestinal tract help in digestion, whereas others like salmonella cause diseases

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    Lichens are unusual. They have neither roots nor leaves, and live in association with a fungus that stores water and nutrients and an alga that synthesizes sugar through photosynthesis

    Algae are plant-like living organisms. They live in the seas, freshwater, or damp land areas. They range from tiny single-celled organisms, which can be seen only under a microscope, to larger plant-like planktons, used as food by blue whales or flamingoes. Large, leaf-like algae, known as 'seaweed', grow extensively in shallow waters to form dense underwater forests.


  • the welwitschia, a plant in the Namib desert in southern Africa, develops only two green leaves during its life? The largest leaf till now was 8 m long and 2 wide.
  • a map-lichen in Greenland has attained the age of 4500 years?
  • in Southeast Asia about 10 tons of algae are eaten every year?