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Structure Of A Dicotyledonous Seed

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  • Last Updated : 31 Aug, 2022
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The study of the physical and external structure of plants is known as the morphology of plants. The morphology of flowering plants includes leaves, roots, stems, flowers, and fruits. Flowering plants are also known as angiosperms. The anatomy of flowering plants includes the organization of cells and tissues within the bodies of flowering plants. Tissues are formed by a group of cells to perform a function. Flowers are known as the reproductive part of the plant since they play the main role in the process of reproduction. 

The flowering plant has two systems which are underground root growth and shoot system. The underground part is known as the root while the above one is named the shoot. 

Plant Structure

 

Roots-The root is a brown, non-green, and underground piece of a plant. Parts of the root include the primary root, lateral roots, the apical meristem, a root cap, and root hairs. The root system of the plants is of 3 types, which are the Taproot system, Fibrous root system, and Adventitious root system.

Shoot-The stem is the ascending part of the axis bearing branches, leaves, flowers and fruits. It develops from the plumule of the embryo of a germinating seed. The shoot system grows above the ground where it assimilates the light required for photosynthesis. The stem consists of nodes and internodes. The district of the stem where leaves are grown is called nodes segments between two nodes are called internodes. The stem bears buds, which might be terminal or axillary.  

Leaves-The leaf is a horizontally borne structure and generally straightened. It is a really photosynthetic piece of the plants. It retains a light and helps in the trading of gases through the stomata. Depending on the pattern of leaf edge, leaves can be additionally characterized into simple and compound leaves. In the simple leaves, the lamina is entire and the lamina does not touch the midrib when incised. In compound leaves, the incisions of the lamina reach up to the midrib breaking it into a number of leaflets. 

Flowers-The flowers are the regenerative part of the plant. A flower is a changed shoot wherein the shoot apical meristem changes to flower meristem. The organization of flowers on the floral axis is called inflorescence which has two significant parts called racemose which let the fundamental node proceed to develop and cymose which ends the primary node in a stream.

Fruits-Fruit is a main element of the flowering plant. It is a full-grown or on the other hand aged ovary, created after fertilization. On the off chance that fruit is shaped without preparation of the ovary, it is known as a parthenocarpic.

The fruit comprises a wall or pericarp and seeds. The pericarp might be dry or meaty. At the point when the pericarp is thick and meaty, it is separated into the external epicarp, the center mesocarp, and the internal endocarp.

Seeds-After fertilization, the ovules develop into seeds that are enclosed in the fruit. These are vital elements in the flowering plant. A seed is comprised of a seed coat and an embryo. The embryo is comprised of a radicle, an embryonal axis, and one or two cotyledons. Depending on the number of cotyledons present in the seeds, they can be classified as monocotyledonous seeds and dicotyledonous seeds.

  • Monocot seeds: In this type of seed, the embryo comprises of embryonal axis and only one cotyledon. Examples include palm trees and onions.
  • Dicot seeds: In this type of seed, the embryo comprises of embryonal axis and two cotyledons. Examples include pea and beans.

Dicotyledons seeds

  • The embryo present in the dicotyledon seed consists of an embryonal axis and two cotyledons. The cotyledons are fleshy, and they are photosynthetic and serve as food reserves for the developing embryo. 
  • The cotyledons are photosynthetic and can produce food for the growing embryo.
  • The outer layer of the dicot seed is called a seed coat. The seed coat has two layers, the outer layer is known as testa, and the internal layer is tegmen. 
  • The scar present on the seed coat is called hilum through which the developing seeds are connected to the fruit. 
  • The small pore present above the hilum is called the micropyle
  • The embryo is enclosed by the seed coat which consists of two cotyledons attached to the primary axis. There are two rudimentary leaves present on the terminal ends in between the cotyledons. One is Plumule which is present on the terminal and the other one is the radicle on the other side of the embryonal axis. 
  • The root is formed from the radicle and the plumule forms the shoot. The region between plumule and micropyle is known as epicotyl and the region between the radicle and micropyle is called the hypocotyl.

In plants like beans, gram, and pea, the endosperm is absent in mature seeds and such seeds are called non-endosperms. Peas, almonds, and cashews are instances of dicotyledons or dicot seeds.

Dicot Root

 

FAQs on Dicot Seeds

Question 1: What are the differences between Monocot and dicot seeds?

Answer:

Dicot seed

Monocot seed

The seed coat is not fused with and it is distinct from the fruit wall The seed coat is completely fused with the fruit wall
Presence of two cotyledons in the seed Presence of one cotyledon in the seed
Endosperm is absent Endosperm is present
Food is stored in two cotyledons Food is stored in endosperm that covers a huge part of a seed
There is no protective sheath for plumule and radicle The plumule is protected by coleoptile and the radicle is protected by coleorhiza.
Example: Bean, Gram Example: Rice, Banana

Question 2: What are the different types of leaves?

Answer:

Leaves can be additionally characterized as simple and compound leaves. In the simple leaves, the lamina is entire and the lamina does not touch the midrib when incised. In compound leaves, the incisions of the lamina reach up to the midrib breaking it into a number of leaflets. 

Question 3: What are the types of compound leaves and the types of compound leaves?

Answer:

In compound leaves, the incisions of the lamina reach up to the midrib breaking it into a number of leaflets.  Compound leaves are classified into two types which are pinnately compound leaves and palmately compound leaves. A number of leaflets are present on a common axis, i.e., the rachis is called pinnately compound leaves (Example-the midrib of the leaf as in neem). When the leaflets are attached at a common point, i.e., at the tip of the petiole are called palmately compound leaves (Example-silk cotton).

Question 4: Explain the modification of stem?

Answer:

Modifications of the stem are as follows

  • Stem Tendrils-These might be extended with flaky leaves. Eg., Antogonon
  • Stem Thorns-These are sharp needle-like designs that are shaped to decrease happening and furthermore go about as a safeguard. Eg., Citrus
  • Phylloclades-These are green, straightened, delicious, leaf-molded structures that perform photosynthesis. They have endless development. Eg., Euphorbia.
  • Cladodes-They is green, photosynthetic of restricted development. The leaves are either adjusted into spines or decreased to scales. Eg., Asparagus

Question 5: What are the different types of roots?

Answer:

  • Taproot system: The main root of the plant is called taproot which is mainly found in the dicot roots.
  • The Fibrous root System: Fibrous roots are mainly found in monocotyledonous plants. These primary roots are short-lived and are replaced by a large number of roots. These roots originate from the base of the stem which constitutes the fibrous root system.
  • The Adventitious root System: The roots that develop from any part of the plant body other than the radicle are called the adventitious root system. This type of root system is mainly found in monocotyledonous plants. 
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