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Nodes and internodes are the organized elements of the vascular plant's stem. The nodes are specific areas which contain lateral buds from which the flower, branches as well leaves arise. The internodes is the distance between two successive nodes from where the xylem and phlegm passes through. The swelling visible on the stem are nodes and occurs in the form of scars on the stem. The gap between the two consecutive nodes are internodes and they help in increasing the height of the plant.
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PhospholipidNode
A specific point on the stem from where leaves start growing is known as Node.
- It is responsible for the vegetative propagation of plants.
- The node contains a lateral bud at the top of the leaflet which either grows as a branch, flower or an aerial root.
- The nodes can be easily identified by the fallen scar of the leaf, even if not the leaf is present.
- The stem must have two nodes, one of them should be buried underground and the other one should be above the ground for growth of the branches.
- The new branches are formed by cutting the stem situated at the top of the nodes.
Nodes
Internode
The area which is surrounded by two consecutive nodes. It helps in maintaining the appropriate distance between two nodes and allow the branches to grow.
- Different plant species have different lengths of internodes. The number of internodes also differs in different plant species.
- The internode is responsible for the increasing length of a plant.
- The tall plants have higher length of internodes and the short plants have smaller internodes.
- As soon as the growing season ends, the length of internodes decreases.
- The xylem and phloem are found in internodes which means the major role of internodes is transportation.
- The xylem transports water from the roots to the leaves.
- The phloem transports food from leaves to storage parts.
Internode
Similarities between the Node and Internode
Similarities between node and internode:
- Two structures in the stem of the vascular plant.
- Have a unique function related to the stem.
- Cells of both internode and node perform the maximum activity.
- The structure of both node and internode are responsible for the plant.
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Difference between Node and Internode
| Node | Internode |
|---|---|
|
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Points to Remember
- Both node and internode are the structure on the stem of a vascular plant.
- Nodes are a part of plant stem from where the growth of leaves takes place while internodes are the part of plant stems between 2 constructive nodes.
- The nodes have axillary buds while internodes do not contain axillary buds.
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Sample Questions
Ques 1. Stem distinctly differentiated into node and internode in
(a) Psilopsida
(b) Lycopsida
(c) Sphenopsida
(d) Pteropsida (2 Marks)
Ans. In sphenopsida the stem is distinctly differentiated into node and internode. This plant is also known as horsetails. Jointed stems mean stems with nodes and internodes along with whorls of leaves and branches that are born at the joints or nodes is the main characteristic of sphenopsida. The stem is vertically ridged at the internodal part of the plant. The sphenopsida consists of upright aerial stems that exhibit a monopodial branching pattern which has one main axis of growth.
Ques 2. Jointed stems with hollow internodes are? (2 Marks)
Ans. Stems are generally divided into nodes and internodes. The nodes hold one or more leaves as well as buds which grow into branches later. Some adventitious roots may also be produced from nodes. Internodes on the other hand are the distance or the part between two nodes. It possesses the ability to stretch, elongate either from its base or from its top depending on the species. If internodal regions grow vertically due to meristem activity or horizontally due to lateral meristem, that is cambium.
Ques 3. Do the branches which arise from the main stem also have nodes and internodes? (1 Mark)
Ans. Yes, all branches have nodes and internodes.
Ques 4. What is the portion between two nodes called? (1 Mark)
Ans. Internode.
Ques 5. Name two plants whose stems are modified to store food in them. (1 Mark)
Ans. Potato and ginger.
Ques 6. Name the three main parts of a leaf. (1 Mark)
Ans. Leaf base, Petiole and Lamina.
Ques 7. What is the relation? (1 Mark)
Ans. The arrangement of veins and the veinlets in the lamina of the leaf is termed venation.
Ques 8. What are the main functions of the stem? (3 Marks)
Ans. The main functions of stem are as follows:
- Spreading out branches bearing leaves, flowers and fruits.
- To conduct water, minerals and photosynthates.
- Some stems perform the function of storage of food, support, protection and vegetative propagation.
Ques 9. What are the functions of petiole? (2 Marks)
Ans. Functions of petiole are as follows:
- The petiole helps hold the blade to light.
- It allows leaf blades to flutter in the wind, thereby cooling the leaf and bringing fresh air to the leaf surface.
Ques 10. What are the functions of lamina? (2 Marks)
Ans. Functions of Lamina
- The veins of the lamina provide rigidity to the leaf blade
- It acts as channels of transport for water, minerals and food materials.
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