MORPHOLOGY OF FLOWERING PLANTS notes
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October 14, 2015 |
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MORPHOLOGY OF FLOWERING PLANTS
Morphology : The study of various external features of the organism is known
as morphology.
Adaptation : Any alteration in the structure or function of an organism or any of
its part that results from natural selection and by which the organism becomes
better fitted to survive and multiply in its environment.
The Root : The root is underground part of the plant and develops from elongation
of radicle of the embryo.
Root Cap : The root is covered at the apex by the thumble-like structure which
protects the tender apical part.
Regions of the root :
1. Region of meristematic activity : Cells of this region have the capability
to divide.
2. Region of elongation : Cells of this region are elongated and enlarged.
3. Region of Maturation : This region has differentiated and matured cells.
Some of the epidermal cells of this region form thread-like root hairs.
Modifications of Root :
Roots are modified for support, storage of food, respiration• For support : Prop roots in banyan tree, stilt roots in maize and sugarcane.
• For respiration : pneumatophores in Rhizophora (Mangrove).
• For storage of food : Fusiform (radish), Napiform (turnip), Conical
(carrot).
The Stem : Stem is the aerial part of the plant and develops from plumule of the
embryo. It bears nodes and internodes.
Modifications of Stem :
In some plants the stems are modified to perform the function of storage of
food, support, protection and vegetative propagation.
• For food storage : Rhizome (ginger), Tuber (potato), Bulb (onion), Corm
(colocasia).
• For support : Stem tendrils of watermelon, grapvine, cucumber.
• For protection : Axillary buds of stem of citrus, Bougainvillea get modified
into pointed thorns. They protect the plants from animals.
• For vegetative propagation : Underground stems of grass, strawberry,
lateral branches of mint and jasmine.
• For assimilation of food : Flattened stem of opuntia contains chlorophyll
and performs photosynthesis.
The Leaf : Developes from shoot apical meristem, flattened, green structure,
manufacture the food by photosynthesis. It has bud in axil. A typical leaf has leaf
base, petiole and lamina.
Venation : The arrangement of veins and veinlets in the lamina of leaf
Types of Venation :
1. Reticulate : Veinlets form a network as in leaves of dicotyledonous plants
(China rose, peepal).
2. Parallel : Veins are parallel to each other as in leaves of monocotyledonous
plants (grass, maize, sugarcane).
Phyllotaxy : The pattern of arrangement of leaves on the stem or branch
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Morphology : The study of various external features of the organism is known
as morphology.
Adaptation : Any alteration in the structure or function of an organism or any of
its part that results from natural selection and by which the organism becomes
better fitted to survive and multiply in its environment.
The Root : The root is underground part of the plant and develops from elongation
of radicle of the embryo.
Root Cap : The root is covered at the apex by the thumble-like structure which
protects the tender apical part.
Regions of the root :
1. Region of meristematic activity : Cells of this region have the capability
to divide.
2. Region of elongation : Cells of this region are elongated and enlarged.
3. Region of Maturation : This region has differentiated and matured cells.
Some of the epidermal cells of this region form thread-like root hairs.
Modifications of Root :
Roots are modified for support, storage of food, respiration• For support : Prop roots in banyan tree, stilt roots in maize and sugarcane.
• For respiration : pneumatophores in Rhizophora (Mangrove).
• For storage of food : Fusiform (radish), Napiform (turnip), Conical
(carrot).
The Stem : Stem is the aerial part of the plant and develops from plumule of the
embryo. It bears nodes and internodes.
Modifications of Stem :
In some plants the stems are modified to perform the function of storage of
food, support, protection and vegetative propagation.
• For food storage : Rhizome (ginger), Tuber (potato), Bulb (onion), Corm
(colocasia).
• For support : Stem tendrils of watermelon, grapvine, cucumber.
• For protection : Axillary buds of stem of citrus, Bougainvillea get modified
into pointed thorns. They protect the plants from animals.
• For vegetative propagation : Underground stems of grass, strawberry,
lateral branches of mint and jasmine.
• For assimilation of food : Flattened stem of opuntia contains chlorophyll
and performs photosynthesis.
The Leaf : Developes from shoot apical meristem, flattened, green structure,
manufacture the food by photosynthesis. It has bud in axil. A typical leaf has leaf
base, petiole and lamina.
Venation : The arrangement of veins and veinlets in the lamina of leaf
Types of Venation :
1. Reticulate : Veinlets form a network as in leaves of dicotyledonous plants
(China rose, peepal).
2. Parallel : Veins are parallel to each other as in leaves of monocotyledonous
plants (grass, maize, sugarcane).
Phyllotaxy : The pattern of arrangement of leaves on the stem or branch
Inflorescence : The arrangement of flowers on the floral axis.
Main types of Inflorescence :
1. Racemose : Radish, Mustard, Amaranthus.
2. Cymose : Cotton, Jasmine, Calotropis.
3. Special type : Ficus, Salvia, Euphorbia.
The Flower : A flower is modified shoot. It is a reproductive unit in angiosperms.
Flowers may be unisexual or bisexual, bracteate or ebractiate. Some features of
flower are as given below :
Parts of flower :
1. Calyx : Sepals, green in colour, leaf like.
2. Corolla : Petals, usually brightly coloured to attract insects for pollination.
3. Androecium : Stamens (filament, anther), male organ and produce pollen
grains. Stamens may be epipetalous (attach to petals) or epiphyloous (attach
to perianth). Stamens may be monoadelphous (united into one bundle), diadelphous
(two bundles) or polyadelphous (more than two bundles).
4. Gynoecium : Made up of one or more carpels, female reproductive part,
consists of stigma, style and ovary, ovary bears one or more ovules. Carpels may
be apocarpous (free) or syncarpous (united). After fertilisation, ovules develop
into seeds and ovary into fruit.
Gamosepalous − (Sepals united)
Polyseptalous − (Sepals free)
Gamopetalous − (Petals united)
Polypetalous − (Petals free)
Perianth : If calyx and corolla are not distinguishable, they are called perianth.
Aestivation : The mode of arrangement of sepals or petals in floral bud.
Types of aestivation :
1. Valvate : Sepals or petals do not overlap the sepal or petal at margins.
2. Twisted : Sepals or petals overlap the next sepal or petal.
3. Imbricate : The margins of sepals or petals overlap one another but not
in any definite direction.4. Vexillary : The largest petal overlaps the two lateral petals which in turn
overlap two smallest anterior petals.
Placentation : The arrangement of ovules within the ovary.
Types of Placentation :
1. Marginal : Placenta forms a ridge along the ventral suture of ovary.
2. Axile : Margins of carpels fuse to form central axis.
3. Parietal : Ovules develop on inner wall of ovary.
4. Free central : Ovules borne on central axis, lacking septa.
5. Basal : Placenta develop at the base of ovary The fruit : After fertilisation, the mature ovary develops into fruit. The
parthenocarpic fruits are formed from ovary without fertilisation.
QUESTIONS
Very Short Answer Questions (1 mark each)
1. Which part of opuntia is modified to form spines ?
2. Name one plant in which leaf is pinnately compound.
3. In mangroves, pneumatophores are the modified adventitious roots. How
are these roots helpful to the plant ?
4. Which part of mango fruit is edible ?
5. Why do various plants have different type of phyllotaxy ?
6. State the main function of leaf tendril.
8. The endosperm is formed as a result of double fertilisation (triple fusion).
What is its function ?
9. Which type of venation do you observe in dicot leaf ?
10. In pea flower, the aestivation in corolla is known as vexillary. Give reason.
Short Answer Questions-II (2 marks each)
11. Flower is a modified shoot. Justify.
12. Name the type of root for the following :
(a) Roots performing the function of photosynthesis.
(b) Roots come above the surface of the soil to absorb air.
(c) The pillar like roots developed from lateral branches for providing
mechanical support.
(d) Roots coming out of the lower nodes of the stem and provide the support
to the plant.
vitamins fat-soluble-vitamins water
the-digestive-system
structure-of-dna
blood-wonder-liquid-part-2
respiration-in-plants
breathing-and-exchange-of-gases
photosynthesis-in-higher-plants
cell-cycle-and-cell-division
transport-in-plants
anatomy-of-flowering-plants
morphology-of-flowering-plants
biomolecules
reproduction-in-organisms
circulatory-system
introduction-of-biochemistry
glycolysis
reproduction
the-male-reproductive-system
human-health-and-diseases
reproductive-health
evolution
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