Structure of Seed


 
 
Concept Explanation
 

Structure of Seed

An angiospermic plant can be divided into two types based on the type of seeds.The two types are :-

Dicotyledonous Seed :-

Structure of Dicotyledonous Seed : -  Seed can be studied under two heads, i.e., external structure and internal structure. It is light or dark brown in colour. Its surface may be smooth or wrinkled. A small oval scar present at the side called hilum. It is the point where the stalk or funicle of the seed is attached to it. A narrow ridge called raphae runs from hilum to chalaza inside the furrow. A small pore called micropyle present between the hilum and pointed end. The outermost covering of the seed is seed coat. The outer hard and leathery layer of the coat is called testa and the inner thin and membranous layer is the tegmen. In some seeds, the tegmen and testa are fused.

The seed coat encloses the embryo, which is differentiated into radicle, a plumule and cotyledons. The radicle develops into root and plumule into shoot. Cotyledons may be one or two to serve as reserve food. Hypocotyl is a part present between the point of attachment of cotyledon and radicle. Epicotyle is present between point of attachment of cotyledons and plumule. In some seeds, such as castor seeds, the endosperm is formed as a result of double fertilisation, which is a food storing tissue. In plants like bean, gram and pea, the endosperm is not present in mature seeds (i.e., non-endospermous seeds).

 Monocotyledonous Seed : -

 The monocotyledonous seeds are endospermic, but some as in orchids are non-endospermic. In the cereals, such as maize, the seed coat is membranous and generally fused with the fruit wall.

Structure of Monocotyledonous Seed : -  The endosperm is bulky and stores food. The outer covering of endosperm separates the embryo by a proteinous layer called aleurone layer. The embryo is small and situated in a groove at one end of the endosperm. It consists of one large shield-shaped cotyledon known as scutellum and a short axis with a plumule and a radicle. The plumule and radicle are enclosed in sheaths which are called coleoptile and coleorhiza, respectively.

Coleoptile has a terminal pore for the emergence of first  leaf during germination. The sheath is capable of growth. It helps the future shoot in passing through the soil during germination, c.g., maize grain is whitish, yellow, violet or red in colour. It has smooth or shiny surface.

Its grain is covered with a single, thin hard covering. It is formed by the fusion of seed coat or testa and the fruit wall or pericarp.

                              

Chapters
Pre-Historic Period
Indus Valley Civilization
Vedic Civilization
Religious Reform Movement
The Early Kingdoms
The Mauryan Empire
Post Mauryan Period
The Age Of The Guptas
Post Gupta Era
Age of Rajput
Khilji Dynasty
Slave Dynasty
Tughlaq and Sayyid Dynasty
Vijaynagar Empire And Bahamani Kingdom
Mughal Empire And Beyond
Lodhi Dynasty
Cholas, Chalukyas and Pallavas
Arab Invasions
Bhakti and Sufi Movement
Rise of Sikhs, Jats and Marathas
Administrative Structure of Delhi Sultanate
Architecture During Medivial India
Advent Of The Europeans
Post Mughal Period
Rise of New States in 18th Century
Growth of British Paramountacy
Socio Religious Reforms
Constitutional Development of India
Indian Struggle Against British Rule
The Revolt Of 1857
Education Under British Rule
Role of Press in Freedom Struggle
First Phase of National Movement
Second Phase of National Movement
Third Phase of National Movement
Constitutional Development in India
Constituent Assembly
Union And Its Territory
Structure of Indian Constitution
Fundamental Rights and Duties
The Union Executive
The Union Legislature
Constitutional Amendments and Provisions
Judiciary In India
Emergency Provisions
Center - State Relations
The State Executive
The State Legislature
Election Commission Of India
Constitutional Organisation
Non-Constitutional Organisation
Local Self Goverment
India - Size And Location
Geological History Of India
The Physical Features Of India
Climate Of India
Soils In India
Natural Vegetation
Windlife Conservation In India
Drainage System of India
Irrigation System Of India
Agriculture In India
Livestock And Fisheries In India
Minerals And Energy Resources In India
Means Of Transport In India
Major Industries In India
Tribes of India
Census of India 2011
Music
Dance
Theatre
Pantings
Art, Architecture & Culture of India
Bio-Diversity
Earth And Its Structure
Land Rock And Soil
Atmosphere, Climate And Weather
Oceanography
Human And Regional Geography
Economic Growth And Development
Sectors Of Indian Economy
Economic Planning Of India
Fiscal And Monetary Policy In India
Infrastructure In India
Effects Of British Rule On Indian Economy
National Income
Banking System In India
Poverty And Unemployment
Inflation And Trade Cycles
Major Institutions
Environmental Studies
Tissues In Organism
Cytology
Classifucation Of Plants
Structural Composition Of Plants
Nutrition In Plants, Harmones And Plant Disease
Ecosystem
Classification In Animals
Nutrition In Animals
Human Digestive System
Human Respiratory System
Human Skeleton System
Human Excretory System
Human Nervous System
Human Circulatory System
Human Endocrine System
Human Reproductive System
Genetics
Human Diseases
States Of Matter
Metals And Non Metals
Acid Bases And Salts
Element Compounds And Mixture
Physical And Chemical Change
Carbon And Its Compounds
Periodic Classification
Fuel, Combustion And Flame
Environmental Chemistry
Rest And Motion
Work Power And Energy
Gravitation
Pressure And Its Effects
Simple Harmonic Motion
Sound and Waves
Heat And Temperature
Light - Reflection
Electricity And Magnetism
Modern Physics
Science And Technology
Force And The Laws Of Motion
Light - Refraction
Dispersion And Human Eye
Magnetic Effect Of Electric Current
Atom And Molecule
Chemistry In Everyday Life
Units And Dimensions
Content / Category
Class / Course
 
 
 
Related Videos
Language - Hindi/English


Students / Parents Reviews [10]