Types of Leaves – Class 11 | Chapter – 5 | Short Notes Series PDF

Types of Leaves: Leaves can be classified into various types based on various criteria such as life span, the shape of the leaf blade and the role they perform in the plant body.

Types of Leaves

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:

  1. Unifoliate: These type of leaves have only one leaflet. Eg., Citrus
  2. Bifoliate: These leaves have two leaflets. Eg., Balanites
  3. Trifoliate: These leaves have three leaflets emerging from the same point. Eg., Oxalis
  4. Quadrifoliate: These leaves have four leaflets arising from the same point. Eg., Marsilea
  5. 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:

  1. Pinnate: A compound leaf that has an axis on each side of the midrib is known as a pinnate leaf.
  2. Unipinnate: The leaf with leaflets on each side of the axis. Eg., cassia
  3. Bipinnate: Here, a secondary axis bearing the leaflet is produced by the central axis. Eg., Acacia
  4. Tripinnate: Here, a tertiary axis bearing leaflets emerges from the secondary axis. Eg., Moringa
  5. Decompound: Leaf with more than three pinnate. Eg., old leaves of coriander
  6. Parapinnate: A leaf without a terminal leaflet. Eg., Cassia
  7. Imparipinnate: Leaf with an odd terminal leaflet. Eg., Pea

Heterophylly 

It is the occurrence of more than one type of leaves on the same plant. It is of three types –

  • Developmental Heterophylly: Leaves of different forms and shape occur at different period or places on the same plant eg. Mustard, Sonchus, Eucalyptus.
  • Environmental Heterophylly: It is aquatic adaptation which is commonly found in rooted emergent hydrophytes. In this, submerged leaves differ from the floating and aerial leaves. eg. Limnophila,
    Heterophylla, Ranunculus aquatiles, Sagittaria.
  • Habitual Heterophylly: Due to habit mature leaves differ in their shape and incissions eg. Artocarpus
    (Jack fruit).

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By Team Learning Mantras