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Morphology of Flowering Plants
The Root
Angiosperms have diverse morphology, still they have the following structures in common:
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Roots
Stem
Leaves
Flowers
Fruits
The Root

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Primary root − direct elongation of radical which grows inside the soil

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Primary root bears several lateral roots termed as secondary roots, tertiary roots, etc
...


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These cells divide repeatedly
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These cells are responsible for growth of root
...


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Epidermal cells of this region form delicate thread-like root hair
...


Characteristics of Root for Absorbing Water
The nature of roots to draw water deep down from the soil depends on three main
characteristics:
1
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Larger the area covered by the roots, more water will be absorbed by them
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Highly Concentrated Cell Sap: The cells of root hairs contain salt-rich cell sap, that makes
its concentration higher than that of the surrounding water
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3
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Structure of a Full Grown Root Hair

Modification of Root
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Roots of some plants modify their structure, shape, etc
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

Modified roots may perform functions such as support, respiration, and storage
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Develops from the plumule of the embryo of a germinating seed

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In growing plants, stem is green in colour, but later it becomes woody and dark-coloured in
trees
...
These structures
also act as organs of perennation to help the plants survive in unfavourable conditions
...
g
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They are present in Citrus, Bougainvillea
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In banana, pineapple, and Chrysanthemum, lateral branches originate from basal
underground portion of main stem
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The Leaf

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The leaf is a lateral, flattened photosynthetic structure originating from the shoot apical
meristems
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Leaves are arranged in an acropetal order
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Bears two stipules (lateral, small leaf-like structure)

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In monocots, leaf base expands to form a sheath that covers the stem totally or partially
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Petiole

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Holds the leaf base to light

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Allows the leaves to flutter and thus, bringing fresh air to the leaf surface

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Lamina or leaf blade

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Green expanded part with midrib and veins

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Veins provide rigidity to the leaf and also help in the transport of water, minerals, and food
...


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Palmately compound leaf − Leaflets are attached at a common point (at tip of petiole as in
silk cotton)
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Peas)
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In insectivorous plants, leaves are modified to trap insects as in pitcher plant
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

In some plants such as Australian acacia, leaves are small and short-lived and petiole
performs the function of leaves
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Flower is a modified shoot
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Internodes do not elongate and axis gets condensed
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When shoot tip is modified into flowers, the flower is always solitary
...
On the thalamus, 4 different
kinds of whorls are arranged:

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Androecium (reproductive organ)

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Gynoecium (reproductive organ)

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Calyx (accessory organ)

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Corolla (accessory organ)

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Perianth − When calyx and corolla are not distinct, together they are called perianth
...


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Based on presence or absence of bracts − reduced leaf found at the pedicel base

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Based on position of sex organs on the thalamus:

Details of Whorls of a Flower



Whorls are arranged on thalamus or receptacle (swollen ends of pedicel)
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Aestivation Mode of arrangement of sepals or petals with respect to other members of the
same whorl:

Androecium
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Male reproductive part composed of stamens

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Each stamen consists of a filament and an anther
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

Sterile stamen is called a staminode
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After fertilization, ovules develop into seeds and ovary into fruit
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During germination, the seed absorbs water
...
e
...

Let us study what happens during germination
When a seed is germinating, the portion above the cotyledon that forms future shoots is
called plumule and the portion below the cotyledon that forms the future roots is called
radicle
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The slide should be kept in such a way that the upper seed is completely out of water,
lower seed is completely submerged in water and the middle seed is half submerged in
water
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Result

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Seed at top − Does not germinate

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Seed at middle − Germinates

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Seed at bottom − Does not germinates
Inference

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Seed at top gets only oxygen and no water
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Seed at middle receives both oxygen and water
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Seed at bottom gets only water and no oxygen
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Activity 2

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Take two petridishes with moist cotton placed in it
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

Place the first petridish in refrigerator (4°C) and the second one at room temperature
(30°C)
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Result

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No germination was seen in the petridish kept in refrigerator while the seed present in the
petridish kept at room temperature germinates
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Structure of Monocot Seed

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In seeds of cereals, seed coat is membranous and fused to the fruit wall
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Endosperm is bulky and stores food
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Embryo consists of

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cotyledon known as scutellum

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embryonal axis (consisting of plumule and radical)

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Plumule is enclosed in a sheath called coleoptile and radical in coleorrhiza
...
Let us see how
these factors affect germination one by one
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Very low or high temperature can destroy the delicate tissues of the seed
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

Epigeal germination

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Hypogeal germination
Epigeal Germination
When the cotyledons are lifted above the ground as a result of rapid elongation of
hypocotyls e
...
seeds of bean, castor, cotton, etc germinate in this manner
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e
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Gram, pea, maize, etc germinate in this manner
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Once germinated, the seedling is dropped into the soil
where it fixes itself by developing roots
...
It consists of roots,
that fix it in the soil and absorb water and minerals, and small young leaves which
manufacture food for it
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Also shows cohesion and adhesion of the parts of whorls and between whorls
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Fruits formed without fertilization of ovary are called parthenocarpic fruits
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In mango, the mesocarp is edible while in coconut, the mesocarp is
represented by the fibrous part
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For example, groundnut
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Family Solanaceae
Family Solanaceae
Solanaceae (potato family)

Vegetative
Characters

Stem

Herbaceous, aerial, erect, branched, hairy, underground
stem (potato)

Leaf

Alternate, simple, rarely pinnately compound, reticulate
venation

Plant

Mostly herbs, shrubs and rarely small trees

Inflorescence Solitary, axillary or cymose
Floral Characters

Flower

Bisexual, actinomorphic

Calyx

Five sepals, gamosepalous, valvate aestivation

Corolla

Five petals, gamopetalous, valvate

Androecium

Five, epipetalous

Gynoecium

Bicarpellary, syncarpous, superior ovary, bilocular,
many ovules

Fruit

Berry or capsule

Floral Formula

Floral Diagram

Family Fabaceae
Family Fabaceae

Fabaceae (bean family)

Vegetative
Characters

Stem

Erect or climber

Leaf

Alternate, pinnately compound or simple, reticulate venation

Plant

Trees, shrubs, herbs, root with nodules

Inflorescence Racemose

Floral
Characters

Flower

Bisexual, zygomorphic

Calyx

Five sepals, gamosepalous, imbricate aestivation

Corolla

Five petals, polypetalous, 1 posterior standard, 2 lateral
wings, 2 anterior ones forming a keel, Vexillary aestivation

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