All flowering plants can broadly be divided into two divisions. They are monocots or monocotyledons and dicot or dicotyledons. Cotyledons are a very important segment of the embryo that lies within the plant’s seed. The structure of monocot and dicot stem is quite different from each other.
Monocotyledons and Dicotyledons
The plants having seeds with two cotyledons are known as dicots, whereas monocots are the plants whose seeds have a single cotyledon. Legumes (like peanuts, beans, lentils), lettuce, mint, tomato, and the like are typical examples of dicots. Again, pulses (including millet, corn, and rice), sugarcane, palm, banana, grass, and the like are an example of monocots.
The ‘cot’ of the plants is actually an embryonic leaf. The cots work to feed the germinating seedlings. This is because the root system of the young plants remains underdeveloped.
There are certain differences between the anatomy of monocot and dicot plants. There are the difference between monocot stem and dicot stem, as well.
In the case of monocot stems, they come with scattered vascular bundles. When the monocot plants mature, they slowly start generating fresh vascular bundles. The bundles are closed and conjoint in structure. They do not come with piths, or the food-transporting tissues in the stalks of young vascular plants. So the vascular bundles stores nutrients within the vascular bundles. However:
- The stems in monocot plants have sclerenchymatous hypodermis or layers of sclerenchyma tissues.
- They work to check water loss from leaves.
- The layers of the tissues are guarded by bundle sheath and noticeable parenchymatous tissues.
- The thick parenchymatous layers transport plant nutrient.
There is a pith zone in the dicot stem. It works as the core around which the intricate vascular bundles are arranged to form a ring. In every bundle of the vascular bundle of a dicot stem, the nutrient bearing xylem and phloem tissues are kept apart by means of the vascular cambium. As the plants mature, the older plant cells are pushed to the edges of the stem. This elongates the vascular bundles. Some more structural features make monocot and dicot stem unique in their own ways. For example:
- The stems have an outer protective layer, called Epidermis.
- The innermost part is called the pericycle.
- The cells in a dicot stem are arranged in different layers. They can be sub-divided into three zones, namely Hypodermis, Cortical Layers, and Endodermis.
- The hypodermis, containing collenchyma cells, give strengthens the new stems.
- Cortical layers, with thin layers of parenchymatous cells, help in the absorption of nutrients and water.
- The ‘starch sheath,’ or endodermis regulate hormone movement, as well as the movement of ions and water in and out of the plant’s vascular system. It also aids in storing plant starch.
- The pericycle present within inner Endodermis offers optimum support and protection to the young plant.
There are a number of differences between monocot and dicot stem. They can be discussed as the following:
The Most Common Differences
|Monocot Stems||Dicot Stems|
|The vascular bundles are present in a scattered manner, without a specific arrangement.||The vascular bundles have a specific shape. They are also arranged in the form of one or two rings.|
|The vascular bundles of the stem are seen in the periphery. These bundles remain guarded by a thick parenchymal layer. However, they have no definite shape.||The wedge-shaped vascular bundles form a ring-like arrangement. They surround a layer of parenchymal tissues.|
|Pith is never present.||There are pith regions.|
|Bundle sheath is present.||Bundle sheath is absent.|
|The hypodermis region is comprised of sclerenchyma cells.||The hypodermis region comprises of collenchymas cells.|
|Do not generate secondary thickening. So the stems do not widen much. There are, however, exceptions like palm and bamboo trees.||Many of the dicot plants can undergo secondary thickening. So all flowering plants with rather thick and woody stems are dicots.|
|Plants cannot form radicles. Hence, the roots crop up from the stem’s nodes.||The lower portion of the seedling’s embryo creates a radical. The roots of the plants are produced from there.|
|Pericycle and phloem parenchyma are not present.||Pericycle and phloem parenchyma there.|
|The vessels have a round or oval shape. They are arranged in a Y-shaped pattern.||The vessels are polygonal in shape. They are arranged in a row or chain shapes.|
|Medullary rays are not present.||Medullary rays are seen between the vascular bundles. They help in radial conduction.|
Here are the answers to some of the most frequently asked questions that highlight the terms related to the difference between monocot stem and dicot stem.
FAQ (Frequently Asked Questions)
- What are the Medullary Rays?
They are vertical rows of parenchymal cells. They run through the vascular tissues of stems and roots in the plants. They work to transport and store plant nutrients.
- What is radical in plants?
It is the very first part of a maturing plant embryo or seedling. During germination, radicals are the first elements to come out of the seeds.
What are Xylem and Phloem?
They are present in the roots and the stems of plants. Typically, Xylem lies within the interior of the stem, while phloem is present on the exterior. Xylem is responsible for carrying minerals and water to the leaves from the roots. Phloem takes the organic nutrients and glucose from the leaves and transports the nutrients to the other parts of the plant.
- What is Parenchyma?
These thin-walled plant tissues are primarily seen in the cortex, pith, or pericycle of the stems and roots. They conduct most of the metabolic activities in a plant.
- What is Sclerenchyma?
They relatively thick and strong plant tissue. They give optimum support to the plant.
- What is Collenchyma?
They are primarily present in the ‘growing parts’ of a plant, such as shoots and leaves. They give additional support to the plants. There is a fundamental difference between sclerenchyma and collenchyma. Unlike sclerenchyma, these tissues generally comprise of thin walls, with irregular, thick patches in the spots where secondary growth is feasible.