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Morphology of Flowering Plants
Morphology is the branch of biological science, which deals with the external structure and features of the living system. It is the study of forms, characteristics and relative positions of various parts of plants.
Morphological study is essential for recognition or identification of plants and knowing the range of variations found in species.
Morphology of flowering plants refers to the study of external features of flowering plants. It explains the structure, functions, classifications, significances and other morphological features of roots, stem, leaves, flower, fruits and the seeds.
The two main external parts of a plant include –Root system and the Shoot system.
The root is the underground part of the plant developed from the seed embryo. Roots are mainly involved in anchoring plants below the soil. It provides support, storing food and nutrients, absorbs water and other essential nutrients required for the growth and development.
The shoot is the upper part of the plant, which is above the root and ground level. The shoot system includes the stem, leaves, bud, flower, fruits and the seeds. It is one of the important systems of a plant.
Flowers are the reproductive part of a plant. They are also a source of food for other living organisms because of its rich source of nectar.
A complete flower consists of sepals, petals, stamens and pistils, and an incomplete flower is the one that lacks one or more of these structures.
A complete flower consists of two different parts: Vegetative and Reproductive
Vegetative Parts of a Flower
The vegetative part of a flower consists petals, sepals
Petals: Petals are bright-coloured parts that attract bees, insects, and birds. It helps us to differentiate one flower from another. Colour of petals varies from plant to plant; some petals are bright and some are pale coloured.
Sepals: Sepal is the green-coloured part beneath the petals to protect buds. Some flowers have fused petals-sepals and others have separated petals-sepals.
Reproductive Parts of a Flower
Flowers contain the plant’s reproductive structures, these reproductive parts are – stamen and pistil. A flower may have only female parts, only male parts, or both.
Male reproductive organ which is also known as Androecium. It consists of two parts: Anther and Filaments.
The anther is a yellowish, sac-like structure, which is involved in producing and storing the pollen.
The filament is a slender, threadlike object, which functions by supporting the anther.
Pistil: This is the female reproductive organ of a flower located in the innermost part. It comprises three parts – stigma, style and ovary.
Stigma: Stigma is the topmost part or receptive tip of carpels in the gynoecium of a flower.
Style: Style is the long tube-like slender stalk that connects stigma and the ovary.
Ovary: Ovary is the ductless reproductive gland that holds a lot of ovules. In this part of seed formation takes place.
Other than vegetative and reproductive parts, a flower is also composed of four whorls, which are responsible for the radial arrangement of a flower.
Every flower has a circular section with a common center, which can be clearly observed from the top of the flower. There are four whorls:
The calyx is the outermost whorl of a flower. It comprises sepals. Tiny leaves that are present at the base of a flower protects the flower whorls against mechanical injuries and desiccation. The calyxes are also called petaloids.
If the sepals are free the calyx is called polysepalous, and if the sepals are united it is called gamosepalous.
In some flowers, the sepals fall off before the flower even opens fully. These sepals are known as caducous. Bit in some, the sepals fall off after fertilization. Such sepals are known as deciduous.
The persistent sepals remain up to the fruiting stage.
Corolla is the second whorl of a flower. It contains petals which serve two main functions: To attract pollinators and To protect the reproductive parts of a flower
Petals are brightly coloured and scented which attracts animals and insects for pollination. The calyx and corolla are collectively called the perianth.
Stamen is the third whorl of the flower and is the male reproductive part. It consists of a filament which is a thread-like structure with a circular structure on the top.
Pollen which is produced by the anther which contributes to the male reproductive process of the plant. Every stamens don’t bear fertile anthers.
The carpel is the fourth whorl of the flower which is present in the centre. They contain the pistil, the female reproductive part of the flower which comprises the ovary, style, and stigma.
Functions Of Flower
The flowers can produce diaspores without fertilization.
The ovary of the flower develops into a fruit containing a seed after fertilization,
Flowers help in the union of male and female gametes.
They provide nectar to certain birds and insects, which in turn help in the transfer of pollen from one flower to the other.
Flowers promote selfing, which means the union of sperms and eggs from the same flower, or cross-fertilization, which means the union of sperms and eggs from different flowers.
Pollination is the process in which the pollen is transferred from anther to stigma. It can occur through a different medium.
The leaf is the most essential part of a plant. Leaves have two functions: photosynthesis and transpiration.
Leaf develops laterally at the node. It is an important part of the shoot system which originates from shoot apical meristems.
Parts of a Leaf
Leaf Base: Part where a leaf attaches to the stem. It has two small leaf-like structures called stipules.
Petiole: Petiole links the leaf blade to the stem.
Lamina: The green, flat surface of the leaves. It is also known as leaf blade. Lamina consists of vein and veinlets.
The vein that runs along the middle of the lamina is called midrib. Veins and veinlets give rigidity to the leaf blade and help in the transportation of water and other substances.
It is the arrangement of veins and the veinlets in the leaves. Different plants show different types of venation.
Functions of Leaves
Photosynthesis converts carbon dioxide, water, and UV light into glucose
It is the removal of excess water from the plants into the atmosphere. This occurs by the opening of stomata present in the leaves.
Guttation is the removal of excess water from the xylem at the edges of the leaves when the stomata are closed.
Leaves store water and nutrients. Succulent and thick leaves adapt to water storage.
Some leaves change into spines to protect them from being damaged or eaten by animals. For eg., Opuntia.
Types of Leaves
There are two types of leaves – simple and compound, which are further divided into different groups based on their shape, size, their arrangements on the stem, leaves of flowering and non-flowering plants, and various other physical attributes.
Simple leaf is when a single lamina is connected to the main stem by a petiole. Example: Guava leaves
A compound leaf is made up of two or more leaflets. In this leaf, the midrib is branched into different leaflets and is connected by a single petiole. For example, Pea, palm leaves.
Roots provide a variety of functions. All plants do not have roots, like mosses and liverworts.
It is the underground part of all vascular plants. This part is mainly responsible for anchoring it down into the ground and absorbing the essential mineral elements, nutrients, and water from the soil. Roots are also used to store food.
Some plants have their roots above the ground which are called aerial roots.
Aerial roots are also responsible for absorbing nutrients, anchoring and affixing the plant by supporting them to the structures such as nearby walls, rocks, trellises, etc.
Few examples of aerial roots are Bonsai, Banyan Tree, Mangroves.
Types of Roots
Taproots are the main central root upon which small, lateral roots called root hairs are attached. e.g. Mustard, carrot, beetroot, parsley, etc.
Fibrous roots are bushy roots in which thin, moderately branching roots grow from the stem, e.g. Rice, wheat, maize, marigold, banana etc.
Functions of Root
Roots perform various functions that are necessary for the survival of the plants. They are:
Anchoring: With the help of roots plants remain attached to the ground. Roots support the plant body, ensuring that it stands erect.
Absorption: Main function of the roots is to absorb water and dissolved minerals from the soil. It helps in the process of photosynthesis.
Storage: Plants prepare their food and store it in the form of starch in the leaves, shoots and roots, e.g. carrots, radish, beetroot, etc.
Reproduction: Though flowers are responsible for reproduction but in some plants, the roots are a means of reproduction.
For example new plants arise from creeping horizontal stems called runners (stolons) in jasmine, grass, etc. This type of reproduction is called vegetative propagation.
Ecological Function: Roots check soil erosion, provide sustenance and also habitat to various organisms.
Fruit And Seed
Fruits are seed bearing dry ripened ovaries of a flowering plant. They are rich in vitamins, minerals and fibres. Apple, orange, papaya, watermelon, etc. are consumed by humans. Fruits are one of the main source of a balanced diet.
Fruits are having two parts: Pericarp and Seeds
The pericarp is the wall of the ovary. It might be fleshy as in guava, mango, etc. or might be dry as in mustard, walnut, etc. The pericarp is further divided into three layers:
Epicarp: Outermost layer which forms the peel.
Mesocarp: Middle fleshy layer which is edible portion of the fruits
Endocarp: Innermost layer. It is the inner rough portion where the seed is accommodated
Seeds are products of ripened fertilized ovules. They are fertilized by pollen and some growth within the mother plant. The embryo develops from the zygote.
The formation of the seed occurs from the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosperm plants.
Ferns, mosses and liverworts do not have seeds and use water-dependent means to propagate themselves.
Types of Fruits
Fruits are classified into three major groups, based on the number of ovaries and the number of flowers involved in the fruit formation.
These kinds of fruits develop from a single matured ovary in a single flower. Apple, banana, plum, etc. The simple fruits are further classified into the following categories:
Drupes: These are also known as stone fruits since they contain a very hard seed inside, e.g.plum, cherry, peach.
Berries: This type of fruit has single seeds in the center and are very juicy. For eg., grapes, blueberries.
Pomes: Such fruits bloom from trees, e.g. apple, papaya
Hesperidium and Pepos: They are similar to the berries and include fruits such as watermelon, citrus fruits.
These kinds of fruits develop from a number of matured ovaries formed in a single flower, e.g. Blackberry, raspberry, strawberry are few examples of aggregate fruits.
These kinds of fruits develop from a complete inflorescence. They are also known as multiple fruits. Composite fruits are of two types:
Sorosis: Sorosis are found in jackfruits and pineapple. They develop from catkin, spikes and spadix type of inflorescence.
Syconus: This fruit develops from hypanthodium type of inflorescence.
In a plant, flowers may grow single or as a group. The inflorescence is the arrangement of a cluster of flowers on a floral axis.
The inflorescence is of two types, they are: Racemose and Cymose
In this type of inflorescence, the flowers branch laterally on the floral axis. Here the floral axis keeps on growing and the flowers develop in an acropetal pattern.
In this type of inflorescence, the flower is the terminating point of each floral axis. In Cymose inflorescence, flowers follow the basipetal pattern of growth.
The main axis branches once or twice in a racemose or cymose manner.
It contains a cup-shaped involucre which is provided with nectar-secreting glands. A female flower, surrounded by male flowers, is enclosed within the involucre.
It is a condensed form of a dichasial cyme with a cluster of sessile and sub-sessile flowers.
The receptacle forms a hollow cavity and has an apical opening protected by scales
Description of families: Fabaceae, Solanaceae and Liliaceae
Fabaceae includes shrubs, herbs, trees and majorly climbers. It is commonly known as the legume, pea, or bean family. There are more than 2000 species that are widely distributed all over the world.
Characteristics of Fabaceae Family
- Root: Taproot with root nodules.
- Stem: Erect or climber;
- Leaves: Petiolate, pinnately compound or simple; pulvinus leaf base, stipulate, reticulate venation.
- Inflorescence: Racemose.
- Flower: Complete, bisexual, zygomorphic Calyx: Five sepals, gamosepalous
- Corolla: Five petals, polypetalous, papilionaceous
- Androecium: Ten stamens, anther dithecous.
- Gynoecium: Superior ovary, monocarpellary, unilocular, flat, hairy-stigma.
- Fruit: Legume.
- Seed: One or more, non-endospermic.
- The plants of this family contain nitrogen-fixing symbiotic bacteria, capable of transforming atmospheric nitrogen into fixed nitrogen or ammonia.
- Pulses like gram, moong, soya bean are the source of food.
- Mulethi plants have medicinal value.
- Soya bean and groundnut oil are used for cooking.
- Sunn hemp is the source of timber and fibre.
- Indigofera is used to make dye.
- Sesbania and Trifolium are the sources of fodder feed.
- Lupin and sweet pea are ornamental plants.
The Solanaceae family is also known as the potato family. It also means the nightshade family. Around 2000 species of dicotyledonous plants belong to Solanaceae family.
It includes a few agricultural crops, medicinal plants, spices, weeds, etc. Some vegetables related to the Solanaceae are Tomatoes, Eggplant, Bell peppers, Chili peppers etc.
Characteristics of Solanaceae Family
- The Solanaceae family includes herbs, shrubs, small trees, and climbers.
- They have a taproot system.
- Their Stem are erect or climber
- Their leaves are alternate, simple or pinnately compound (rarely)
- Inflorescence: Racemose- terminal
- Flower: Complete, bisexual, actinomorphic
- Calyx: Five sepals, gamosepalous
- Corolla: Five petals, gamopetalous,
- Androecium: Five stamens, epipetalous
- Gynoecium: Syncarpous, bicarpellary, bilocular
- Fruit: Berry/ capsule.
- Seed: Numerous, endospermous
- Important source of food. E.g. tomato, brinjal and potato
- Important sources of spices. E.g. chilly
- The leaves of Nicotiana tabacum are a major source of tobacco.
- Used as ornamental plants. E.g. petunia
- Plants such as belladonna and ashwagandha are used as medicinal plants.
Liliaceae is the family of around 2500 species of perennial, herbaceous monocots. It is also known as the ‘lily family’. Its characteristics are discussed below. Liliaceae includes perennial herbs which propagate through bulbs or rhizomes.
The leaves of this family are linear in shape, with their veins usually arranged parallel to the edges. A few Liliaceae genera are popular cultivated plants such as Aloe vera.
Characteristics of Liliaceae Family
- Root: Fibrous root system.
- Stem: Erect
- Leaves: Alternate, simple
- Inflorescence: Cymose- solitary
- Flower: Complete, bisexual, actinomorphic
- Perianth: Indistinctive sepal and petal
- Androecium: Six stamens in two whorls
- Gynoecium: Syncarpous, tricarpellary
- Fruit: Mostly Capsule and sometimes berry.
- Seed: Endospermic seeds.
- Source of Medicine -Aloe vera, Smilax and Colchicine.
- Ornamental Plants -Lilium, tulips, Gloriosa and Ruscus.
- Source of food- Asparagus.
Also Read Chapter 4: Animal Kingdom
Frequently Asked Questions
Q1. What is morphology?
Answer: Morphology is the branch of biological science, which deals with the external structure and features of the living system.
It is the study of forms, characteristics and relative positions of various parts of plants.
Q2. What are the parts of plant?
Answer: The two main external parts of a plant include –Root system and the Shoot system.
Q3. How many types of plant family are there?
Answer: There are three types: Fabaceae, Solanaceae and Liliaceae
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