Plants can be classified into various categories depending on various features.
On the basis of FLOWER
Flowering also called Angiosperms : Sun flower, Rose, tomato
Non- Flowering also called Gymnosperms: Pines,ferns,mosses.
On the basis of their Size, Type of Stem, spread of branch, plants are classified into 3 categories:
Herbs
Shrubs
Trees
Characteristics
Herbs
Shrubs
Trees
Size
Short plants with height less than 1m
Medium-sized plants with height around 1-3m
Tallest plant with height more than 3-4 m
Nature of stem
Green and tender stem, have a few branches
Hard & woody stem, not very thick.
Thick
Type of branches
Branches are either absent or present sparsely
Branches arise from the base of the stem giving it a bushy appearance
Branches arise from the upper part of the stem at some distances from the ground. Some trees like coconut tree are branch less; they have only one stem that bears leaves, flowers and fruits
Examples
mint, tomato, spinach, wheat, paddy, grass etc.
Rose, lemon, henna, hibiscus etc
Banyan, mango, neem cashew, oak etc
Certain plants have weak steams and cannot stand upright. They are categorised into two types: Creepers
The stems of these plants spread/trail on the ground.
Stems are long, thin and fragile and cannot stand erect.
Examples – water melon, strawberry, pumpkin, sweet potato etc
Climbers
More advanced than creepers.
They have thin long and weak stems that cannot stand upright but they can use external support to grow vertically and carry their weight.
These types of plants use special structures called tendrils to climb.
Examples – pea plant, grapevine, money plant, etc.
SOME OTHER TYPES OF PLANTS
MOSS
Small non flowering green plants.
Grow in damp and shady areas.
GRASS
Flowering plants.
Short in height.
Long narrow leaves.
AQUATIC PLANTS
Grow in water only.
They are either rooted in mud under water (lotus) or float without any anchorage (water hyacinth) other e.g. water lilies, hydrilla & tape grass.
PARTS OF A PLANT
Root System- Non-green part of the plant present under the ground. Contains Main root and Lateral roots.
One thick vertical root called Primary root with many lateral roots arising from it.
Example: Rose, pea, Dahlia, Gram.
Fibrous Root
Arise as a tuft from base of stem. Usually short-lived.
Example: Grass, maize, wheat and rice.
FUNCTIONS OF ROOTS.
Absorption of water and nutrients from the soil.
Anchors the plant to the soil.
MODIFICATIONS OF ROOTS
Modifications- Roots performing special functions other than their normal functions. For this, they undergo few changes in their appearance. Food storage
Tap roots store food for unfavourable conditions.
Can be eaten and are called Edible Roots.
Example: Carrot, beetroot, radish, sweet potato.
Extra Support
Prop Roots
Roots grow as pillars to support weak stem or heavy branches.
Example: Banyan tree.
Stilt Roots
Roots arise from stem to give support to weak stem.
Example: Maize
Climbing Roots
Roots help weak stems to climb up a support.
Example: Money Plant and Black Pepper.
SHOOT SYSTEM-STEM
Main part of shoot stem.
Bears branches, leaves, flowers, buds and fruits.
Stem has two main parts- Node and Internode
Node- Point from where leaf or a branch arises. Several nodes are present in a stem
Internode- Portion of stem between two nodes.
FUNCTIONS OF STEMS:
Keeps plant upright.
Helps in Transportation of water, minerals, and food to different parts.
MODIFICATIONS OF STEMS
Providing Support
Tender, coiled structures called tendrils coil around any support.
Present in weak stems. Called climbers or twiners.
Example: Grapevines
Food storage
Underground stems store food.
Example: Potato, onion, ginger.
Making food
Green and fleshy stem.
Can perform photosynthesis and store water.
Example: Cactus.
LEAF
Responsible for carrying out photosynthesis.
PARTS OF LEAF:
Lamina – flat broad part of leaf, receives solar radiation during photosynthesis.
Petiole – small stalk which attaches the lamina to the stem.
Veins – lines running through the leaves, responsible for transfer of water and minerals in the leaves.
Midrib – thicker line/vein in the middle of a leaf.
VENATION
FUNCTION OF VEINS
(a) Distributes water and minerals throughout the leaf.
(b) Gives support
TYPES OF VENATIONS:
Parallel venation – veins run parallel to each other from the petiole to the tip of the leaf, found in the leaves of grasses, cereals (wheat, rice) and banana.
Reticulate venation – several small veins/veinlets arise from the midrib, found in the leaves of mango, Hibiscus, rose, tulsi, papaya etc.
FUNCTIONS OF LEAVES
Photosynthesis- KITCHEN OF PLANT
Presence of stomata on the surface of leaves helps in gaseous exchange.
Transpiration – loss of water in the form of vapour from leaves. Helps in
Maintaining temperature.
Absorption of more water and minerals from the soil.
MODIFICATIONS OF LEAF.
Spines –
reduces the surface area of leaves and minimizes the loss of water due to transpiration.
defence mechanism of plants to prevent animals from eating them.
found in desert plants.
Pitcher –
Seen in insectivorous plants.
Modified leaves (pitchers) capture insects to fulfil their nitrogen requirement (nitrogen is required for protein synthesis)
Pitcher plants grow in nitrogen deficient soil.
These plants can also make food through photosynthesis
Tendrils
Tip of leaves gets modified to tendrils.
Provide extra support to plants.
Found in pea plant, Gloriosa, cucumber plant etc.
FLOWER
Modified shoot. Develops from bud.
Reproductive organ.
Attractive- Colourful petals or fragrance.
Develops into fruit.
STRUCTURE OF FLOWER
SEPAL- Outermost part. Green and leafy. Protects flower in bud stage.
PETAL- Colourful or white. Vary in shape and size. Attract insects and birds.
STAMEN- Male Reproductive part.
Anther- Sac like structure containing pollen grains.
Filament- Slender stalk like structure.
PISTIL/CARPEL- Female Reproductive organ.
Stigma- Uppermost part. Brush like appearance. Might be sticky to catch pollen.
Style- Middle tube like part.
Ovary- Lower swollen portion containing ovules. Ovary forms fruits and ovule forms seeds.
THALAMUS/RECEPTACLE- Swollen portion at base of flower. All parts are attached to it.
PEDICEL/PEDUNCLE- Stalk of the flower.
POLLINATION
It the transfer of pollen to a stigma, ovule, flower, or plant to allow fertilization.
It is of two types
SELF-POLLINATION
In self-pollination, the pollen from the anther of a flower is transferred to the stigma of the same flower or the stigma of a different flower on the same plant. CROSS-POLLINATION
In cross-pollination, the pollen from the anther of a flower on one plant is transferred to the stigma of the flower on another plant of the same species. After pollination
Ovary – forms fruit
Ovule – forms Seeds
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