Let's start by knowing different parts of any plant which will help us to understand the differences between plants of different kinds. Below image illustrate different parts of a plant:
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| Parts of a plant |
HERBS, SHRUBS AND TREES:
Most of the plants can be classified into three categories i.e. herbs, shrubs and tress based on following characters:
- Height of plant.
- Thickness of stem / Tender or Hard stem ?
- Where do the branches appear? At base of stem or higher up on the stem?
Herbs: Plants with green and tender stems are called herbs. They are usually short and may not have many branches. Tomato is an example of herb.
Shrubs: Some plants have the stem branching out near the base. The stem is hard but not very thick. Such plants are called shrubs. Lemon is an example of shrub.
Trees: Some plants are very tall and have hard and thick brown stem. The stems have branches in the upper part, much above the ground. Such plants are called trees. Mango is an example of tree.
Creepers and Climber: Plants with weak stems that cannot stand upright and spread on the ground are called creepers, while those that take support on neighbouring structures and climb up are called climbers. These are different from the herbs, shrubs and trees. Money plant, beanstalk, gourd plants and grape vines are example of climbers.
STEM:
Stem is the part of plant which conducts water. Water moves up the stem. Minerals dissolved in water also move up in the stem, along with the water.
The water and minerals go to leaves and other plant parts attached to the stem, through narrow tubes inside the stem.
LEAF:
A leaf usually has a petiole and a lamina. The part of a leaf by which it is attached to the stem is called petiole. The broad, green part of the leaf is called lamina.
Visible lines on the leaf as shown in below figure are called veins. A thick vein in the middle of the leaf is called the midrib.
The design made by veins in a leaf is called the leaf venation. It can be reticulate or parallel. If this design is net-like on both sides of midrib, the venation is reticulate [Fig (a)]. In the leaves of grass, veins are parallel to one another. This is parallel venation [Fig (b)].
Tulsi, coriander (dhania), China rose leaves etc. shows reticulate venation, whereas wheat, maize and grass leaves shows parallel venation.
Visible lines on the leaf as shown in below figure are called veins. A thick vein in the middle of the leaf is called the midrib.
The design made by veins in a leaf is called the leaf venation. It can be reticulate or parallel. If this design is net-like on both sides of midrib, the venation is reticulate [Fig (a)]. In the leaves of grass, veins are parallel to one another. This is parallel venation [Fig (b)].
Tulsi, coriander (dhania), China rose leaves etc. shows reticulate venation, whereas wheat, maize and grass leaves shows parallel venation.
Functions of leaves:
- Leaves give out water vapour through the process of transpiration. Plants release a lot of water into the air through this process.
- Green leaves make their food by the process of photosynthesis using carbon dioxide and water in the presence of sunlight. Oxygen is given out in this process.
ROOT:
This is the part of plant which remains inside soil. The roots help in holding the plant firmly in the soil. They are said to anchor the plant to the soil.
Roots absorb water and minerals from the soil and the stem conducts these to leaves and other parts of the plant. The leaves prepare food. This food travels through the stem and is stored in different parts of a plant. We eat some of these as roots—like carrot, radish, sweet potato, turnip and tapioca.
There are two types of root:
Roots absorb water and minerals from the soil and the stem conducts these to leaves and other parts of the plant. The leaves prepare food. This food travels through the stem and is stored in different parts of a plant. We eat some of these as roots—like carrot, radish, sweet potato, turnip and tapioca.
There are two types of root:
- Taproot: Fig (a) illustrates a plant with taproot. Main root is called taproot and the smaller roots are called lateral roots.
- Fibrous root: Plants with roots as shown in Fig. (b) do not have any main root. All roots seem similar and these are called fibrous roots.
Leaf venation and the type of roots in a plant are related in a very interesting way. Plants having leaves with reticulate venation have tap roots while plants having leaves with parallel venation have fibrous roots.
FLOWER:
Main parts of a flower are sepals, petals, stamens and pistil.
- Most prominent parts of a open flower are the petals of flower. Different flowers have petals of different colours.
- Sepals are the most prominent part in a bud. This part is made of small leaf like structures. Petals are covered with sepals in a bud.
- The innermost part of a flower is called the pistil, which can be further divided into ovary, stigma and style.
- Ovary of a flower is the lowermost and swollen part of the pistil.
- After cutting an ovary, we see some bead like structure inside the ovary which are called ovules.
- Structure of the flower is not always the same.
- The number of sepals, petals, stamens and pistils may also be different in different flowers. Sometimes, some of these parts may even be absent!
Notes: Marigold, chrysanthemum or sunflower are not single flowers, but, groups of flowers.
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