5.1 Dr.Katherine Esau: (1898-1997)
She first reported in her publication that the curly top virus spreads through a plant via the food conducting or phloem tissue.
Dr. Esau published Plant Anatomy (1954) and The Anatomy of Seed Plants (1960).
In 1957, she was elected to the National Academy of Sciences, becoming the sixth woman to receive that honor.
Peter Raven, director of Anatomy and Morphology, Missouri Botanical Garden, remembered that she ‘absolutely dominated’ the field of plant biology even at the age of 99.
5.2 Introduction: Savinay Kumar JC
The study of external features of an organism is called Morphology.
All angiosperms are characterized on the bases of morphological structures like Root, Stem, Leaves, flowers and fruits.
Understanding Standard Terminology: To classify and understand higher plants well, it's important to know the basic technical terms and definitions.
5.2.1 Adaptations in Plant Structures:
Plant parts may exhibit significant variations to suit their environment. These adaptations include:
Habitat adaptations: Plants may modify their structures based on where they live (e.g., desert, aquatic environments).
Protection adaptations: Thorns or spines or toxic or hallucinates may develop to protect plants from herbivores.
Climbing adaptations: Specialized structures like tendrils help plants climb and reach sunlight.
Storage adaptations: Some plants store water or nutrients in their roots or stems (e.g., tubers)
Majorly the plant is divided into two regions;
Root System: The underground part of the plants is called Root system.
Shoot System: An aerial part of the plant above the ground is called the Shoot system.
5.2.2 Difference between Dicot and Monocot Plants:
*Flower Parts = Sepals and Petals
5.3 The Root:
In Vascular Plants, the root is an organ of a plant that typically lies below the surface of the soil (Root System).
Due to this it is a descending part of the plant body.
The first root that comes from a plant embryo is called the radicle (germinated root at seed level).
5.3.1 Main Functions of the roots:
The functions of the roots are as follows;
Absorption of water and minerals from soil.
Anchoring (stay in one position) of the plant body to the ground and supports.
Synthesis of plant growth regulators.
Storage of food and nutrients.
It helps in Vegetative reproduction.
5.3.2 Types of Roots:
Based on the structure and radicle the roots are classified into three types as follows;
Tap roots
Fibrous Roots and
Adventitious roots
5.3.2.1 Tap Roots: Savinay Kumar JC
It is the root system of dicotyledonous plants, the radicle develops into primary roots (main root or mother root), it bears lateral roots (secondary and tertiary roots) and grows vertically in the soil. In this primary root is perennating.
Ex: Pea Plant, Mustard Plant etc.
5.3.2.2 Fibrous Roots:
It is the root system of Monocotyledonous plants. The primary root is short lived (which originated from radicles) and is replaced by a large number of roots. These roots originate from the base of the stem (lower nodes).
Ex: Sugarcane, Maize Rice, Wheat etc.
Note: Fibrous root is also a type of Adventitious root.
5.3.2.3 Adventitious Roots:
Roots arise from parts of the plant other than the radicle called Adventitious roots. These roots arise above the ground level.
Ex: Grass, Sugarcane, Monstera and Banyan tree.
5.3.3 Regions of the Root:
The root is covered at the apex or tip by a thimble (cap) like structure called root cap. It protects the young tip of the root and it makes way through the soil.
A few millimeters above the root cap is the region of meristematic activity. The cells in this region are very small, thin-walled, contain dense protoplasm and undergo rapid division. This continuous cell division is essential for root growth.
The meristematic region undergoes rapid elongation and enlargement of root in length. This region is called the region of elongation.
The cells of an elongation zone gradually differentiate and mature. This region is known as the region of maturation.
The region of maturation contains epidermal cells. It forms very fine and delicate, thread like structures called root hairs. These root hairs absorb water and minerals.
5.3.4 Modification of Root:
Roots in some plants modified to perform other than absorption of water and minerals.
They are modified for support, storage of food and respiration.
Storage Roots: The roots are modified to support storage of food. It is also known as Swollen roots.
Ex:1 Carrot, Radish, and Turnip (Beetroot) are Tap roots.
Ex: 2 Sweet Potato, Agave and Orchids have Adventitious roots.
Mechanical Support Roots: These roots support the plant. Like Prop roots and Stilt roots.
Prop Roots: It is an aerial root that arises from a stem or branch, penetrates the soil and helps to support the plants. Ex: Banyan tree, and Rubber tree.
Stilt Roots: The roots that arise from lower nodes of the stem supporting the plant are known as stilt roots. Ex: Maize and Sugarcane.
Pneumatophores Roots
The many roots come out of the ground and grow vertically upwards or above the soil. Such roots are called pneumatophores.
It is also known as pencil roots.
It helps to respiration and absorption of humus in the environment.
Ex: Rhizophora, Mangrove species, Asparagus etc.
Note:
In many aquatic plants, roots are absent due to limited necessity of water and minerals absorption. Ex: Wolffia, Utricularia and Ceratophyllum.
Few plants are grouped under Dicot but its roots are fibrous , for example Sweet Potato, Ground Nut, Cotton Plants, Beans family etc,. Because of adapting to specific growth conditions or evolutionary paths.
5.4 The Stem:
In vascular plants, the stem is an organ of a plant that lies above the surface of the soil or aerial part of the plant (shoot system).
The stem is the central axis or ascending parts of the shoot system bearing branches, leaves, flowers, fruits, internodes and nodes.
The stem arises from the plumule of the embryo during seed germination.
The stem bears buds, which may be terminal or axillary.
The region of the stem where leaves and bud are born are called nodes.
The portion or gap or space between two nodes are called Internodes.
Difference between root and stem:
5.4.1 Functions of the Stem:
Primary Functions:
Spreading out branches of the stem bearing leaves, flowers and fruits.
It conducts water, minerals and food.
Secondary or Specialized Functions:
It takes place in photosynthesis.
Storage of food.
It helps in the support and protection.
It helps in vegetative propagation (asexual reproduction).
5.4.2 Modification of Stem:
The Stem modified to perform other than transport of water, minerals and food.
Storage or Underground Stems: The stem is modified to store food or helps at unfavorable conditions to provide nutrients to the plant that's why it is also called a perennating organ. Ex: Potatoes, Ginger, Turmeric, Zaminkand and Colocasia.
Stem Tendrils: It is developed from axillary buds, slender and spirally coiled. It helps plants to climb. Ex: Cucumber, Pumpkins, Watermelon and Grapevines.
Stolons or Runners or Propagation Stems: Underground stems of some plants that grow along the soil surface (horizontally). Ex: Grass and Strawberry.
Cladophylls or Phylloclades (Gr: Phyllo = leaf; clado = branch/ stem): Stems are modified for photosynthesis. Ex: Cactus or Opuntia, Euphorbia.
Thorn: A modified stem with a sharpened point arises from axillary buds. They protect plants from browsing animals. Ex: Citrus, Rose, Bougainvillea etc. Savinay Kumar JC
Woody: Hard brown textured stems and straight. Ex: Neem tree, Banyan tree etc.
Pseudostem: A false stem made of the rolled bases of leaves and main stem grow horizontally beneath the soil. Ex: Banana, Pineapple and Chrysanthemum (Sevanthi).
Offset: A lateral branch with short internodes and each node bearing a rosette of leaves and a tuft of roots is found in aquatic plants. Ex: Pistia and Eichhornia
5.5 The Leaf: Savinay Kumar JC
A leaf is a lateral, flattened organ that is borne on the stem of a vascular plant.
The leaves and stem together form the shoot.
The leaf develops at the node and bears a bud in its axil. The axillary bud later develops into a branch.
Leaves originated from shoot apical meristems and are arranged in an acrophyll order (most plants, Ex: Neem leaves) or in a basophyll order (few plants, Ex: Curry leaves).
5.5.1 Functions of Leaves:
Main function of the leaf is Photosynthesis.
Helps in exchange of gasses (respiration)
Helps in Storage of food and
It cools the plant (in summer season).
5.5.2 Main Parts of the Leaf:
A typical leaf consists of three main parts as follows;
Leaf base
Petiole and
Lamina
Leaf Base:
The leaf base helps in attaching the leaf to the stem.
Leaf base bears two lateral small leaf-like structures called Stipules. It helps in protection of young leaves and buds.
In Monocots, the leaf base expands into a sheath covering the stem partially or wholly.
In some leguminous plants the leaf base may become swollen (inside the stem) is called Pulvinus.
Petiole: Savinay Kumar JC
It helps to hold leaf blades or Lamina.
The flexible and long petiole helps in cooling the plant with the help of lamina.
Furthermore, it serves in exposing the leaf's lamina to sunlight.
Lamina: Savinay Kumar JC
It is also known as leaf blade.
It contains fleshy part veins and midrib (thick, middle prominent vein on lamina).
Veins provide rigidity to the lamina and act as channels of transport for water, mineral and food materials.
The shape, margin, apex, surface and extent of incision of lamina varies in different leaves.
5.5.3 Venation:
The arrangement of veins and the veinlets in the lamina of leaf is known as Venation.
Venations are two types on the bases of arrangement of veins on lamina as follows;
Reticulate Venation and
Parallel Venation
Reticulate Venation: The veins are interconnected and the network form in the leaf is known as reticulate venation. Ex: Dicot Plants like Hibiscus, Rose, Mango, Pupil etc.
Parallel Venation: The veins are parallel to each other within a lamina of leaf is known as parallel venation. Ex: Gymnosperm and Monocot Plants like Coconut, Grass, maize, Sugarcane etc.
Extra Information:
Circinate Vernation: The Veins of leaf in Coil form are known as Circinate vernation. Ex: Dryopteris (in young Pteridophytes but adult shows Reticulate Venation).
5.5.4 Types of Leaves:
There are two types of leaves based on the number of leaflets, midrib and lamina as follows;
Simple Leaf and
Compound Leaf
5.5.4.1 Simple Leaf:
The number of leaflets is one for one petiole and the incision of the lamina does not touch the midrib is known as simple leaf.
Ex: Mango, Hibiscus, Pea, Papaya, Castrol etc.
5.5.4.2 Compound Leaf:
The Number of leaflet is more than one for one petiole and the incision of the lamina touching the midrib is known as Compound leaf.
Compound leaves divided into two types based on the resemble as follows;
Pinnately compound leaf: In this the number of leaflets are present on a common axis called rachis (It acts like both midrib and petiole). Ex: Neem Leaves, Curry Leaves etc.
Palmately Compound Leaf: The leaflet attached at a common point or tip of petiole is called Palmately Compound Leaf. Ex: Silk Cotton leaf.
Note: A bud is present in the axil of petiole in both simple and compound leaves, but not in the axil of leaflets of the compound leaf.
5.5.5 Phyllotaxy: (Gr: Phyllo = leaf; taxy = arrangement)
Phyllotaxy is the mode of arrangement of leaves on the stem or branch. It is three types as follows;
Alternate Phyllotaxy
Opposite Phyllotaxy and
Whorled Phyllotaxy
i. Alternate Phyllotaxy: A single leaf arises at each node. Ex: China rose, Mustard Leaves and Sunflower Plants.
ii. Opposite Phyllotaxy: A pair of leaves arises at each node and lie opposite to each other. Ex: Neem, Guava Leafs and Calotropis.
iii. Whorled Phyllotaxy: If more than two leaves arise at a node and form a whorl. Ex: Alstonia leaves.
5.5.6 Modification of Leaf:
Leaves modified to perform other than photosynthesis.
Tendrils: The leaves are modified in the form of spiral or coiled form known as tendrils. It helps with climbing. Ex: Peas and Bitter Gourd.
Spines: The leaves are modified in the form of sharp ends or sharp points known as spines. It helps for defense and protection from herbivore organisms. Ex: Euphorbia and Cactus.
Storage Leaves: The leaves modified to store food are known as storage leaves. Ex: Onion, Garlic and Aloe Vera.
Trap Leaves: These leaves are modified to trap insects and kill because of Nitrogen deficiency in the soil. These leaves are also called insectivorous leaves or carnivorous leaves. Ex: Pitcher plant and Venus fly trap.
Phyllode (Gr: Phyllo = leaf; ode = resemble): The petiole or rachis modified for photosynthesis. Ex: Australian acacia. This is because the leaves are small and short-lived.
5.6 Inflorescence: (Lt: come into flower)
The arrangement of flowers on a floral axis is known as Inflorescence. (or)
It is a single or cluster of flowers arranged on a stem or branch.
5.6.1 Types of Inflorescences:
Depending on whether the apex gets converted into a flower or continue to grow, inflorescence are divided into two types as follows;
Racemose and
Cymose.
5.6.1.1 Racemose:
It is a type of inflorescence where the main axis continues to grow and the flowers are born laterally in acropetal order.
Ex: Mango, Mustard, Radish, Eucalyptus etc.
5.6.1.2 Cymose: Savinay Kumar JC
It is a type of inflorescence, the main axis terminates in a flower, hence is limited in growth.
The flowers are borne in a basipetal order.
Ex: Lily, Hibiscus, Lotus etc.
5.7 The Flower: Savinay Kumar JC
The flower is the reproductive unit in the angiosperms.
It is meant for sexual reproduction.
It is a modified shoot wherein the shoot apical meristem changes into floral meristem.
Internodes do not elongate and the axis gets condensed.
The apex produces different kinds of floral appendages laterally at successive nodes instead of leaves (give rising flowers instead of leaves).
When a shoot tip transforms into a flower, it is always solitary but in a few cases clusters.
The study of flowers is known as Anthology.
Cultivation and marketing of flowers is known as floriculture.
5.7.1 Parts of a typical Flower:
A typical flower has a stalk of flower called Pedicel.
Enlarged or Swollen end or the terminal part of the pedicel is called Thalamus or Receptacle.
On the thalamus four whorls (Floral parts or Floral appendages) are arranged: Calyx, Corolla, Androecium and Gynoecium.
Calyx and Corolla are non essential parts or accessory parts of the flower because they do not participate in reproduction.
Androecium and Gynoecium are essential parts or reproductive parts of the flower because they participate in reproduction.
In some flowers like Lily, the calyx and corolla are not distinct is known as perianth. It is made up of tepals.
5.7.1.1 Calyx:
It is the outermost non essential whorl of the flower.
A group of sepals is known as calyx.
Generally, sepals are green, leaf-like and protect the flower in the bud stage.
A condition in which sepals are free is known as Polysepalous. Ex: Mustard.
A condition in which sepals are fused known as Gamosepalous. Ex: Hibiscus.
5.7.1.2 Corolla:
It is a secondary non-essential whorl of the flower.
A group of petals in a flower is known as Corolla.
Petals are usually brightly colored to attract insects for pollination.
A condition in which petals are free is known as Polypetalous. Ex: Hibiscus.
A condition in which petals are fused is known as Gamopetalous. Ex: Datura.
The shape and color of corolla vary greatly in plants.
Shapes of Corolla may be tubular, bell shaped, funnel-shaped or wheel-shaped.
5.7.1.3 Perianth:
It is the outermost whorl of the flower without distinct calyx or corolla.
A group of tepal in flower is known as perianth.
This condition is usually seen in monocot plants.
A condition in which tepals are free is known as polytepalous. Ex: Champaka
A condition in which tepals are fused is known as gamotepalous. Ex: Lily
5.7.1.4 Aestivation:
Mode of arrangement of petals and sepals in the flower bud is known as Aestivation.
They are five types of aestivation as follows;
Valvate Aestivation: Petals and sepals margins not overlapped in flower bud. Ex: Calotropis and Sunflower.
Imbricate Aestivation: When one of the sepal or petal is internal being overlapped on both the margins, one of them is external and remaining members, one margin is internal and other is external.
Or
When the margins of petals or sepals overlap one another without any specific direction. Ex: Gulmohur and Cassia (Cinnamon Plant).
Twisted Aestivation: The sepals or petals of the margin is one external and one internally overlapped. Ex: Hibiscus, China Rose, Lady’s Finger and Cotton.
Vexillary Aestivation:
It is universally found in all Papilionaceous corolla. It consists of the large petal called Standard, which covers the two lateral petals called wings. They in turn enclose two small petals called Keel which are united to form a boat-like structure. Ex: Pea and Bean.
Quincuncial Aestivation: There are five petals, in which two are completely internal, two are completely external and the remaining members are overlapped at their margin. Ex: Guava and Tobacco.
5.7.1.5 Androecium:
Androecium is a male reproductive organ of a flower in seed plants or flowering plants.
It is an essential part of the flower.
It is composed of stamens. Each stamen consists of filament (stalk-like structure) and anther lobe.
Types of Anther:
Bilobed: The most common type, with two lobes.
Unilobed: Rarely found, with only one lobe.
Production of pollen grains:
Each lobe has two chambers called the pollen-sacs.
The pollen grains are produced in pollen-sacs.
A sterile stamen is called staminode.
5.7.1.5.1 Characteristics of Androecium:
Cohesion of stamens: Stamens may be free or united. Based on united of stamens following types;
Polyandrous: These flowers have free stamens. Ex: Hibiscus.
Syngenesious: Filaments free and anthers united. Ex: Sunflower
Synandrous: Both filaments and anthers fused. Ex: Cucurbita and Pumpkin.
Adelphous: Anthers are free and filaments are fused.
Monadelphous: United to form 1 bundle. Ex: China Rose.
Diadelphous: United to form 2 bundles. Ex: Pea.
Polyadelphous: United into more than 2 bundles. Ex: Citrus.
Adhesion of stamens: Fusion of stamens with other parts of the flower.
Epipetalous: Stamens fused with petals. Ex: Brinjal.
Epiphyllous: It is also known as Epitepalous. Stamens fused with tepals. Ex: Lily
Note:
Gynandrous: Stamens attached to carpels Ex: Calotropis
Attachment of filament to anther:
Basifixed: Filament attached to the base of an anther lobe. Ex: Mustard
Adnate: Filament contains either side of an anther lobe or filament between an anther lobe. Ex: Magnolia, Champaka
Dorsifixed: Filament attached to the back of an anther or dorsal side of an anther. Ex: Passion flower, Cotton
Versatile: An anther lobes in crescent (half moon) shape. The filament is attached to an anther lobe in the middle portion and both ends are free. Ex: Gramineae family (grass).
Dehiscence pattern: The splitting or releasing pollen grains from mature anther lobes.
Porous: Pollens release through pores. Ex: Brinjal and Potato
Longitudinal: Pollens released through the longitudinal slit of the anther lobes.
Note: There may be a variation in the length of filaments within a flower called Dimorphic, as in Salvia (didynamous = 2 long stamens and 2 short stamens) and mustard (tetradynamous = 4 long stamens and 2 short stamens).
5.7.1.6 Gynoecium: Savinay Kumar JC
Gynoecium is the female reproductive part of the flower and it is made up of one or more carpels (megasporophylls).
It is also one of the essential parts of the flower because it participates in reproduction.
A carpel consists of three parts namely stigma, style and ovary.
Ovary is the enlarged basal part, on which lies the elongated tube, the style. Each ovary bears one or more ovules attached to a flattened, cushion-like placenta.
The style is an elongated tube connecting the ovary to the stigma.
The stigma is usually at the tip of the style and is the receptive (accept) surface for pollen grains.
5.7.1.6.1 Characteristics of Gynoecium:
Position of the Ovary: Based on the position of the ovary on thalamus, the flowers are three types as follows;
Hypogynous Flower: This flower ovary occupies above the thalamus while calyx, corolla and androecium situated below the ovary due to this ovary is called superior ovary. Ex: Mustard, China Rose and Brinjal.
Perigynous Flower: This flower ovary situated little inside the thalamus and surrounded by calyx, corolla and androecium due to this ovary is called semi superior or semi inferior ovary. Ex: Plum, Rose, and Peach.
Epigynous Flower: This flower ovary situated inside the thalamus and above the ovary, calyx, corolla and androecium located. This ovary is called an inferior ovary. Ex: Guava, Cucumber and Apple.
Cohesion of Carpels: Carpels are fused or free based on this, it is divided into two types as follows; Savinay Kumar JC
Apocarpous: Carpels are free. Ex: Rose, Champaka and Lotus.
Syncarpous: Carpels are fused or united. Ex: Hibiscus, Ladys Finger, Mustard and Tomato.
Placentation: Mode of arrangement of ovules within the ovary is known as placentation. Based on the position of ovule in the ovary is divided into following types;
Marginal Placentation: The ovules are attached on the ventral margin in the ovary. Ex: Fabaceae (Beans family or Leguminosae).
Axile Placentation: The Ovules are attached to the center of the axile (septum) within the ovary. Ex: China rose, Tomato, and Lemon.
Parietal Placentation: The ovules are attached to the inner wall of the ovary with one chamber. Ex: Cucumber and Papaya, but in mustard and Argemone observe false septum due to these two chambers.
Basal Placentation: The ovule arises from the basal part of the ovary. Ex: Sunflower, Mango, and Marigold.
Central and Free Central Placentation: The ovules arise from the center of the ovary. Ex: Chilly, Dianthus and Primrose.
Number of locules in Ovary: The cavity, chamber, or free space within the ovary that contains the ovules is known as a locule.
Marginal, Basal, central and free central Placentation is monolocular.
Axile Placentation is multilocular.
Parietal Placentation is monolocular and in few cases bilocular due to the formation of the false septum. Ex: Mustard and Argemone.
5.7.2 Sexual Type in Flower:
When a flower has both androecium (male sex organ) and gynoecium (female sex organ) is called a bisexual flower. Ex: Hibiscus, Mustard, Mango etc.
A flower having either only stamens (Staminate) or only Carpels (Pistillate) is called a unisexual flower. Ex: Maize, Papaya, Coconut etc.
5.7.3 Symmetry of Flowers:
When a flower can be divided into two equal halves in any plane of the axis passing from the center is known as an Actinomorphic flower. Ex: Hibiscus, mustard, datura, chili.
When a flower can be divided into two equal halves in any one plane of the axis passing from the center is known as an Zygomorphic flower. Ex: pea, gulmohur, bean, Cassia etc.
When a flower can not be divided into two equal halves in any plane of the axis passing from the center is known as an Asymmetric flower. Ex: Canna.
5.7.4 Bract:
Bract is a small leafy structure present at the base of the flower or inflorescence.
A flower with bract is called a bracteate flower. Ex: Hibiscus
A flower without a bract is called an ebracteate flower. Ex: Champaka, Lily etc
Function: Bract helps in attraction of insects for pollination and also helps in protection of flower buds along with sepals.
5.7.5 Trimerous, Tetramerous and Pentamerous flowers:
Trimerous Flowers have floral appendages in multiples of three. Ex: Maize, Wheat, Rice.
Tetramerous Flowers have floral appendages in multiples of four. Ex: Mustard, Radish.
Pentamerous Flowers have floral appendages in multiples of five. Ex: Hibiscus, Vinca rosea, Lily.
5.8 The Fruit: Savinay Kumar JC
Mature and ripen ovary after fertilization is called fruit. Savinay Kumar JC
Study of fruits is known as Pomology.
Development of fruits without pollination and fertilization is called Parthenocarpic fruits (Partheno = Virgin/no coitus/no pollination; carpic = fruit). Ex: Pineapple, Banana, Papaya, Grapes etc.
5.8.1 Pericarp:
The wall of the fruit is known as Pericarp. It is also known as Periwall.
It is formed from an ovary wall. It may be fleshy or dry.
It is differentiated into an outer layer called Epicarp, middle layer called Mesocarp and inner layer called Endocarp.
Note: Savinay Kumar JC
Mango and coconut fruits are drupes.
Drupes are developing from monocarpellary (single-chambered) superior ovaries and contain one seed.
Epicarp of Mango and Coconut is outer skin.
Mesocarp in Mango is fleshy and edible while in Coconut is fibrous and non-edible.
Endocarp in Mango is Hard Stony layer while in Coconut is hard woody layer.
5.9: Seed:
Mature, ripened and fertilized ovules are called Seeds.
Study of seeds called Spermology.
5.9.1 Types of Seeds:
Based on number of cotyledons, it is divided into two types as follows;
Dicotyledonous Seeds and
Monocotyledonous Seeds.
5.9.1.1 Structure of Dicotyledonous Seeds:
Seed is kidney or spherical shaped with concave and convex sides.
A seed is made up of a seed coat and an embryo.
The outermost covering of a seed is the seed coat.
The seed coat has two layers, the outer testa and the inner tegmen.
Seed coat has a whitish, elongated ridge called ‘Raphe’.
At the basal portion of the raphe there is a distinct broad scar known as Hilum. Through which the developing seeds were attached to the fruit. Savinay Kumar JC
Above the hilum is a small pore called the Micropyle.
The embryo is made up of an embryonal axis and two cotyledons.
At the two ends of the embryonal axis are present the radicle and the plumule.
The cotyledons are often fleshy and full of reserve food materials.
5.9.1.2 Structure of Monocotyledonous Seeds:
Monocotyledonous seeds are endospermic but some as in orchids (ex: Vanilla) are non-endospermic.
In the seeds of cereals such as maize the seed coat and pericarp are fused and form a hull.
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 and shield shaped cotyledon known as scutellum.
Scutellum has a short axis with a plumule and a radicle.
The plumule and radicle are enclosed in protective sheaths called coleoptile and coleorhiza respectively.
5.9.2 Difference between Endospermic and Non Endospermic seeds:
Note:
Endosperm is the nutritive tissue developed from Primary Endosperm Nucleus (PEN).
Perisperm is the nutritive tissue of a seed derived from the nucellus and deposited external to the embryo sac.
5.10 Semi Technical Description of a Typical Flowering Plant:
Various morphological features are used to describe a flowering plant.
The description has to be brief, in a simple, scientific language and presented in a proper sequence.
The plant is described beginning with its habit, vegetative characters – roots, stem and leaves and then floral characters like inflorescence and flower parts.
After describing various parts of the plant, a floral diagram and a floral formula are presented.
Fusion is indicated by enclosing the figure within brackets and adhesion by a line drawn above the symbols of the floral parts.
A floral diagram provides information about the number of parts of a flower, their arrangement and the relation they have with one another.
The position of the mother axis with respect to the flower is represented by a dot on the top of the floral diagram.
Calyx, corolla, androecium and gynoecium are drawn in successive whorls, calyx being the outermost and the gynoecium being in the center.
Floral formula also shows cohesion and adhesion within parts of whorls and between whorls.
5.10.1 Description of Family: Brassicaceae
Ex: Mustard;
Scientific Name: Brassica nigra
5.10.2 Description of Family: Solanaceae
Ex: Potato;
Scientific Name: Solanum tuberosum
It is a large family, commonly called the ‘potato family’. It is widely distributed in tropics, subtropics and even temperate zones.
Vegetative characters:
Plants mostly herbs, shrubs and rarely small trees.
Stem: herbaceous rarely woody, aerial; erect, cylindrical, branched, solid or hollow, hairy or glabrous (smooth and hairless), underground stem in potato (Solanum tuberosum)
Leaves: alternate, simple, rarely pinnately compound, exstipulate; venation reticulate.
Floral Characters: Savinay Kumar JC
Inflorescence: Solitary, axillary or cymose as in Solanum.
Flower: bisexual, actinomorphic.
Calyx: sepals five, united, persistent (remain long period of time), valvate aestivation.
Corolla: petals five, united; valvate aestivation.
Androecium: stamens five, epipetalous
Gynoecium: Bicarpellary obligately placed, syncarpous; ovary superior, bilocular, placenta swollen with many ovules, axile.
Fruits: berry or capsule (cotton).
Seeds: many, endospermous.
Economical Importance:
Many plants belonging to this family are the source of food (tomato, brinjal, potato), spice (chili); medicine (belladonna, ashwagandha); fumigatory (tobacco); ornamentals (petunia).
