Questions covered are:
Characteristics of Herbs and Shrubs:
Characteristics of Shrubs and Trees:
Characteristics of Climbers and creepers.
Plant System
Tap root and fibrous root system:
Fibrous roots and adventitious roots:
Prop root and Stilt root
Assimilatory, Haustoria and Breathing roots
Functions of the Root:
MODIFICATIONS OF THE ROOT:
STEM
Functions of Stem:
MODIFICATIONS OF STEM:
THE LEAF
Parts of the Leaf:
FUNCTION OF LEAF:
MODIFICATIONS OF LEAF:
FLOWERS AND FRUITS
POLLINATION:
Types of Pollination:
What happens if the pollinators go extinct?
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Plants grow both in land and water
There are about 2,50,000 types of Plants
There are two broad group of Plants
- Flowering plants – Ex: Rose, Sunflower, Mango
- Non Flowering Plants – Ex: Ferns, Mosses
Based on their size and nature of their stem, plants are classified into Herbs, Shrubs and Trees
Characteristics of Herbs and Shrubs:
| Herbs | Shrubs |
| Very small, usually less than 1m high. | Medium sized, usually 1-3 m high |
| Green tender stem, few branches. | Hard stem but not very thick, branches arise near the base of the stem. |
| Grass, tomato, wheat, mint | China rose [hibiscus], lemon, rose, and pomegranate. |
Characteristics of Shrubs and Trees:
| Shrubs | Trees |
| Medium sized, usually 1-3 m high. | Tall, generally more than 3m high. |
| Hard stem but not very thick; branches arise near the base of the stem. | Hard brown, thick tem, branches on the upper part of the stem. |
| China rose [hibiscus], lemon, rose, and pomegranate. | Flame tree [Gul mohar], neem, peepal, mango. |
Other than Herbs, Shrubs, Trees there are also Creepers and Climbers
Characteristics of Climbers and creepers.
| Climbers | Creepers |
| Plants has weak stem that take support on neighbouring structures. | Plants has weak stems that cannot stand erect, and creep on the ground. |
| Coiled tendrils help the plant to climb the support[ nearby trees, wooden poles] | Fibrous roots develop at every nodal point on the stem below and shoots above the ground. |
| Ex: Grapevine, gourd, money plant, cucumber, beans, peas etc.. | Ex: Watermelon, pumpkin, strawberry, sweet potato etc.. |
Plant System
Plant have two parts. They are Root system, Shoot system
Difference between the Root system and shoot system:
| Root system | Shoot system |
| The underground part of the plant or the part that remains in the soil is called the root system. | The green part of the plant that grows above the ground is called shoot system. |
| It consist of main root and number of branching roots. | It consists of the stem, leaves, buds, flowers and fruits. |
| Tap root and fibrous roots are the two types of root system. | Vegetative and reproductive system are the two types. |
There are two major type of Root system. They are Tap Root and Fibrous Root.
Tap root and fibrous root system:
| Tap root system | Fibrous root system |
| The main root that arises from the radicle of the seed is called tap root. | A number of thin fibre like roots arise from the base of the stem other than radicle of the seed is called fibrous root system. |
| The branches that arise from the main root is called secondary roots are lateral roots. The lateral roots further branches to tertiary roots and root hairs | The fibre like roots give rise to many thin root hairs. |
| Tap root grows deep into the soil. Example; pea, Tulsi mango. | They spread out in the soil. Example; maize, wheat, barley. |
Fibrous roots and adventitious roots:
| Fibrous roots | Adventitious roots |
| A number of thin fibre like roots that arise from the base of the stem other than radicle of the seed is called fibrous root system. | Roots that arise from any part of the plant body [branches, leaves, stem, and roots] is called adventitious roots. |
| The fibre like roots give rise to many thin root hairs. | They can help in giving support, photosynthesis, breathing, storage, haustoria roots. |
| They spread out in the soil. Examples; maize, wheat, barley , rice | They do not mostly spread in the soil. Example; sugarcane, mangrove plants, carrot, cuscuta |
Tap root and Storage roots
| Tap root | Storage roots |
| The main root that develops from the radicle of the seed. | The main root that develops from the radicle of the seed. |
| They grow deep in the soil, and obtain nutrients from the shoot system. | They too grow deep in the soil, but store excess food which are used during unfavourable conditions. |
| Example; mango tree, neem tree, peepal tree etc., | Example; carrot, turnip, beet root. |
Prop root and Stilt root
| Prop root | Stilt root |
| The roots that grows from the branches of the banyan tree vertically downwards to support the huge tree is called prop roots | The roots that arise from the lower nodes of the stem and grows vertically downwards to give support to plants are called stilt roots. |
| The prop roots act like pillars of the buildings. | The stilt roots gives additional support to tall, slender plants like sugarcane, maize. |
Assimilatory, Haustoria and Breathing roots
| Assimilatory roots | Haustoria roots | Breathing roots |
| The roots of tinospora, water chestnut develop roots aerially, turn green to prepare food. | The roots of Cucuta, mistletoe [parasitic plants] develop a special kind of roots called haustoria roots for growth and reproduction. | The roots of the mangrove plants growing in marshy soil develop erect roots aerially above the water logged soil to breathe in oxygen. |
| The green colour of the roots is due to the presence of chlorophyll. | The haustoria roots penetrate into the tissues of the host plant and suck all the nutrients. | The aerial roots develop small pore on the surface of the roots called as pneumatophores. |
Functions of the Root:
- Root anchor the plants firmly to the soil
- Roots absorb water and minerals present in the soil
- Water and mineral salts from the soil reach the stem and branches through a thin tubes present in roots and stem
- Roots bind the soil particles together and prevent soil erosion
MODIFICATIONS OF THE ROOT:
Other than the basic function of the root, Roots are modified into various structures to perform other functions
1. Roots are modified to store food. Ex: Radish, Carrot, Turnip.
Foods made in the green leaves travel downwards and is stored in the tap root.
2. Roots are modified to give extra support.
Ex: Banyan tree has roots that grow down from its branches, they fix in the soil and give support to the huge trees. They are called as Prop roots
Big banyan tree in Kolkata has more than 900 Prop roots
STEM
Functions of Stem:
- The Stem keeps the plant upright.
- The Stem bears branches, leaves, buds, flowers and fruits
- Stem conducts/transports the food prepared by leaves, water and minerals to all parts of the Plant
- Thin tubes from roots are connected to thin tube of stem through which water and minerals are transported
- Food prepared by leaves are transported to all parts of through another set of thin tubes
MODIFICATIONS OF STEM:
Stems are modified to give support.
Ex: Grapevine, Gourd, Passion fruit plants have stem tendrils. These coil around the rough surface to give support
Stems are modified to store food:
Ex: Ginger, Potato are modified Underground stem storing food
Stems are modified to make Food:
Ex: Cactus ( in deserts) Green stem in cactus prepares food and it is fleshy to store water. To prevent the loss of water, leaves are modified to spines
THE LEAF
Parts of the Leaf:
- The flat green portion of leaf is called as Lamina/ Leaf blade
- Lamina is attached to the Stem by a short stalk called as Petiole
- Petiole continues in the leaf as midrib that branches to form network of lines called Veins
- Arrangement of leaves in vein is called as leaf venation
- When the veins are parallel to the length of leaf it is called as Parallel venation Ex: Fibrous root plants
- When the veins form net like structure / design on both sides of leaf, it is called as Reticular venation. Ex: Tap root plants
- Function of Veins in leaf is to transport water, minerals and food
- Veins it provides support to the plant
FUNCTION OF LEAF:
- Leaves are green in colour due to the presence of green pigment called as Chlorophyll
- Conditions required by the plants to make food is
- Proper sunlight
- Water from soil
- Carbon dioxide in air
- Chlorophyll
- Process of making food by leaves with the help of sunlight, carbon dioxide, chlorophyll is called as Photosynthesis
- Food prepared by leaf is a sugar called Glucose
- Plants stores the extra food in fruits, roots, stem or leaves as Starch
- Presence of Starch is identified by Iodine solution
- Iodine Solution + Starch = Blue black colour
- Plants release water through Stomata present in leaves. This process is called as Transpiration
- Transpiration plays an important role in Water cycle, by increasing the moisture content in the air
MODIFICATIONS OF LEAF:
- Leaves are modified to give support.
- Upper leaflets of Glorosia plant is modified to tendrils to give support
- Leaves are modified into spines, to avoid loss of water through transpiration and to protect the plant from grazing of animals Ex: Cactus
FLOWERS AND FRUITS
- The most attractive part of Flowering plant is Flowers
- Most flowers are brightly coloured and scented to attract insects
Structure of a Flower:
- Flower has a stalk called Pedicel which joins it to stem
- Uppermost part of the Pedicel is Thalamus
- Different parts of flower are arrangement in Whorls
- Outermost Whorl are green leaf like structure called as Sepals that protect the flower in Bud stage
- Next to Sepals is Petals. They are brightly coloured to attract insects
- Next to Petals, Stamens (Male part of the Plant) is present
- Stamen consist of thin green stalk/ Filament with bag like head called Anther
- Anther consist of Pollen grains , dust like particles. They take part in Reproduction
- In the centre of the flower rises flask shape structure called Pistil/ Carpel
- Pistil/ Carpel is the female part of the flower
- Its base is slightly swollen called as Ovary
- The Short tube like upper part is a style and above is Stigma
- Stigma receives the Pollen grains from anthers
- Inside the Ovary, small bead like structure called ovules are present
POLLINATION:
- Pollen grains from anther are transferred to stigma of same flower or another flower by wind, water, insects. This process is called as Pollination
- After pollination, Ovules swell up and change into fruit and in some plants they change into seeds
Types of Pollination:
Self-Pollination: Pollination that occurs within the same flower
Cross Pollination: Pollination that occurs between two different flowers of same species.
Autogamy: It is a type of self-pollination where the transfer of pollen grains from the anther to the stigma takes place within the same flower EX: Sunflower, peas, orchids, Groundnut.
Allogamy: The transfer of pollen grains from the anther of a flower on one plant to the stigma of a flower on another plant of the same species is called Allogamy. EX: cotton, sorghum, Pigeon pea
Geitonogamy: Geitonogamy is the type of self pollination where the transfer of pollen grains from the anther to the stigma takes place between different flowers in the same plant. EX: Corn
Xenogamy: Xenogamy is the cross-pollination where the pollen grain transfer occurs across flowers of two different plants. EX: onion, spinach, broccoli
Pollinating agents are abiotic and biotic factors. Abiotic factors (non living ) are wind and water. Biotic factors (living things) are birds, insects etc.
Pollination through insects is called as Entomophily Ex: Rose, Jasmine etc.
Pollination through birds is called as Ornithophily Ex: Hibiscus, Eucalyptus etc.
Pollination through bats is known as Chiropterophily. Ex: Cactus. This type of pollination occurs mainly in tropical and desert areas
What happens if the pollinators go extinct?
- If the pollinators will extinct ,the plants will also extinct.
- There will be no pollinators to transfer the pollens. so the plants will also extinct.
- Many fruits and vegetable are insect pollinated and could not be grown large scale and so cheaply.
Fruit is made up of fruit wall and seeds
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