The circulatory system is a common feature in human beings, animals, and plants. Plants also feature a venation system in their leaves. The arrangement of leaves in a specific pattern is venation. The venation system is an important topic in the NEET exam. It is important to know the different venation classifications and how to differentiate between parallel and reticulate venation.
Veins are a part of the vascular tissue that emerge from the stem and extend to the tip of the leaves. Veins consist of xylem and phloem and enclose sclerenchyma and parenchyma, which is surrounded by sheath cells. Venation is nothing but the arrangement of leaves in a leaf, and it is prevalent amongst a diverse set of plant species.
Furthermore, venation is integral in identifying and differentiating plants with their features. Venation is helpful in mechanical assistance, protection, development, and coordination between parts of a plant. Learn more about what is venation, its importance, and different kinds of venation in plants.
What is Venation?
The word venation is derived from “veins”, and the veins’ arrangement on leaves is called venation. Veins are present in the vascular tissue of the plant. The tissues emerge from the stem and extend until the tip of the leaf. The figure below shows a common venation found in a leaf:
The stem constitutes the xylem and the phloem. Xylem and phloem also enclose the layers of cover around them. These layers are called the parenchyma and sclerenchyma, which are surrounded by the sheath cells. The primary function of these are the same, yet there are some differences.
Importance of Venation
As venation runs from the stem to the leaves, it benefits the entire plant and the leaves. A few things that venation helps the plants are:
- Physical support
Venation runs to the tips of the leaves and provides physical support to the leaves. It helps the blades to maintain their shape and structure during their lifespan.
- Coordination
With the process of venation, leaves can coordinate with other parts of a plant. It protects the blade as a whole.
- Transporting nutrients
Venation helps to carry the nutrients to the leaves, which assist in growth. This helps in the overall development of the blade.
- Identifying plants
Venation is different for different plants. This helps to identify the specific plant by viewing the formation of the veins.
- Classification
Once a plant species is identified through the venation, it can be utilised for classification.
Venation is not consistent and is different in different plants. It will now help to look further into the different kinds of venation- parallel and reticulate.
All about Parallel Venation
Parallel venation is a situation in leaves when all the veins starting from the base of the leaf or petiole are parallel to each other to the tip of the leaf. Typically, this is a distinctive feature of monocot plants and relates to the broad shape of the leaf and broad base.
Veins run parallel to one another from the base of the leaf ( called the petiole) to the tip of the leaf ( called the apex). This forms a pattern like a net on either edge of the midrib. There are two kinds of parallel venation – Pinnately and Palmately.
- Pinnate Parallel Venation/Unicostate Parallel Venation
Veins emerge from the prominent midvein found in the middle of the leaf lamina from the base to the apex. Here veins develop in a perpendicular pattern to the midvein close to the margin and are parallel. The best example of this kind of venation can be seen in banana leaves.
- Palmate Parallel Venation/Multicostate Parallel Venation
In this kind of venation, several veins will come from the tip of the petiole and will run parallel to each other. They meet at the apex. Several prominent veins will appear as if running parallel to each other. It can, in turn, be of two types- convergent parallel venation and divergent parallel venation.
When the veins seem to emerge from the midrib, run parallel to it, and meet at the apex of the leaf, it is categorised as convergent parallel venation. A perfect example of this kind of venation could be found in grass or Borassus. If the leaf is disconnected into lobes and a vein separately enters into each lobe, it can be categorised as divergent parallel venation. A good example of this would be the palmyra palm.
What is Reticulate Venation
Reticulate venation is a common characteristic in dicot leaves. The veins form an interrelating network that spreads all over the lamina.
The primary vein or midrib joins the leaf in this kind of venation. The midrib comprises several branches that branch out to tiny secondary veins.
These secondary veins spread starting from the midrib to the margin of the leaf. Examples of this type of venation include ficus, guava, china rose, holy basil, white teak, mango hibiscus, physic nut etc. Reticulate veins can be divided into two types:
- Pinnate Reticulate Venation/Unicostate Reticulate Venation
Only one midvein will be present, with the other veins forming a structure similar to a mesh. A perfect example would be the Mangifera leaves.
- Palmate Reticulate Venation/Multicostate Reticulate Venation
Veins form a network, and one can find midribs. This venation could be of two kinds- convergent and divergent reticulate venation.
Difference between parallel and reticulate venation
The table below lists the points that highlight the differences between parallel and reticulate venation.
Parallel | Reticulate |
Meaning | |
Veins appear parallel to each other all through the lamina or leaf blade. The veins run parallel from the base to the tip. | Veins are arranged like a network or in the form of a web. The veins appear in a web-like structure right from the lamina or leaf blade. |
Orientation of veins | |
Veins are parallel to each other | Veins appear in a web-like structure |
Found in | |
Monocots | Dicots |
Examples of plants where it is found | |
Bamboo, banana, wheat, maise, grass | Mango, Hibiscus, Ficus |
Similarities between Parallel and Reticulate Venation
One of the main correspondences between parallel and reticulate venation are:
- Both contain xylem and phloem that play an important role in the transportation and translocation of food and water all through the leaf.
- Both parallel and reticulate venation offer automated support and coordination during the development of the leaf blade.
Conclusion
One of the key topics in botany, differentiation between parallel and reticulate venation, carries a lot of weightage in terms of marks. The above explanation delves deep into the meaning, difference, and examples of both these classifications.