Plants can be classified into tree categories: Herbs, Shrubs and Trees.
- Herbs: Plants with green and tender stems. They are usually short and may not have many branches.
- Shrubs: They have the stem branching out near the base. The stem is hard but not very thick.
- Trees: They are very tall and have hard and thick brown stem. The stems have branches in the upper part, much above the ground.
- Creepers: They are plants with weak stems that cannot stand upright and spread on the ground.
- Climbers: Plants that take support of neighbouring structures and climb up.
Water moves up the stem or the stem conducts water. 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.
- 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.
- The lines on the leaf are called veins.
- The thick vein in the middle of the leaf is called midrib.
- The design made by veins on a leaf is called the leaf venation.
- If the design is net-like on both sides of midrib, the venation is reticulate.
- In the leaves of grass, the veins are parallel to one another. This design is called parallel venation.
- Water comes out of leaves in the form of vapour by a process called transpiration.
- Leaves prepare their food in the presence of sunlight and a green coloured substance present in them. For this, they use water and carbon dioxide from air. This process is called photosynthesis. Oxygen is given out in the process. The food prepared by leaves ultimately gets stored in different parts of the plant.
The stem supplies leaf with water. The leaf uses the water to make food. The leaves also lose water through transpiration. How do the stem and leaves get the water? That is where the roots come in.
- Type of Roots:
- The roots help in holding the plant firmly in the soil. They anchor the plant to the soil.
- Here, the main root is called taproot and the smaller roots are called lateral roots.
- Fibrous Roots: There is no main root and all roots seem similar as shown below.
- Plants having leaves with reticulate venation have tap roots while plants having leaves with parallel venation have fibrous roots.
- 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. So the stem is like a two-way street.
- The prominent parts of an open flower are the petals.
- The prominent part of a bud is made of small leaf-like structures called sepals.
- The innermost part of a flower is called the pistil.
- Parts of a stamen
- Parts of a pistil
- Ovary is the lowermost and swollen part of the pistil.
- Small bead-like structures inside the ovary are called ovules.
- The number of sepals, petals, stamens and pistils may be different in different flowers. Sometimes, some of them may even be absent.
Read More: Chapter 5&6