A Write the types of leaves.
Answers
Answer:
Types of Leaves
There are two broad categories of leaves – simple and compound, which are further classified 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.
The two different types of leaves found in a plant are:
Simple Leaf
When a single lamina is connected to the main stem by a petiole, the leaf is said to be simple. A simple leaf may be incised to any depth but not down to the midrib or petiole. Eg., Guava leaves
Compound Leaf
A compound leaf is a leaf made up of two or more leaflets. In a compound leaf, the midrib of the leaf is branched into different leaflets and is connected by a single petiole. For eg., Pea, palm leaves.
The compound leaves are further sub-divided into the following types of leaves:
Palmately Compound Leaf
In a palmately compound leaf, the leaflets are attached at the tip of the petiole. Eg., Silk cotton. These can be differentiated into:
Unifoliate: These type of leaves have only one leaflet. Eg., Citrus
Bifoliate: These leaves have two leaflets. Eg., Balanites
Trifoliate: These leaves have three leaflets emerging from the same point. Eg., Oxalis
Quadrifoliate: These leaves have four leaflets arising from the same point. Eg., Marsilea
Multifoliate: This type of leaf has many leaflets arising at a common pint. Eg., Bombax
Pinnately Compound Leaf
In a pinnately compound leaf, the midrib of the leaf is divided into numerous leaflets and all connected by a common axis. Eg., Neem. These can be further differentiated into:
Pinnate: A compound leaf that has an axis on each side of the midrib is known as a pinnate leaf.
Unipinnate: The leaf with leaflets on each side of the axis. Eg., cassia
Bipinnate: Here, a secondary axis bearing the leaflet is produced by the central axis. Eg., Acacia
Tripinnate: Here, a tertiary axis bearing leaflets emerges from the secondary axis. Eg., Moringa
Decompound: Leaf with more than three pinnate. Eg., old leaves of coriander
Parapinnate: A leaf without a terminal leaflet. Eg., Cassia
Imparipinnate: Leaf with an odd terminal leaflet. Eg., Pea
Modification Of Leaves
We know leaves are specialised to perform photosynthesis. In addition, they also have other significant roles to play, such as support, storage of food, defence, etc. For each of these functions, they have been modified into different forms.
For example, tendrils of peas, spines of cacti, onion bulb, leaves of insectivorous plants, etc. are different modified leaves. Let us have a detailed look at some of the modification of leaves:
Functions of Leaves
The leaves perform the following functions:
Photosynthesis
Photosynthesis is the primary function of leaves. They convert carbon dioxide, water, and UV light into glucose through the process of photosynthesis.
Also Refer: Photosynthesis
Transpiration
Transpiration is the removal of excess water from the plants into the atmosphere. This occurs by the opening of stomata present in the leaves.
Guttation
Removal of excess water from the xylem at the edges of the leaves when the stomata are closed is known as guttation.
Storage
Leaves are a site of photosynthesis. Therefore, they store water and nutrients. The succulent and thick leaves particularly adapt to water storage.
Defence
Some leaves are modified into spines to protect them from being damaged or eaten by animals. For eg., Opuntia.
Key Points
Leaves are found at the nodes of the stem and contain the photosynthetic pigment chlorophyll.
There are three main parts of a leaf – Leaf base, leaf lamina, and petiole.
There are two different types of leaves – simples leaves and compound leaves. The other types of leaves include acicular, linear, lanceolate, orbicular, elliptical, oblique, centric cordate, etc.
They perform the function of photosynthesis and help in the removal of excess water from the aerial parts of the plant.
They are modified in the form of spines, tendrils, hooks and scales and help them to adapt to various environments.