Types of leaves its modification and function | study science

Types of leaves

There are two categories in which leaves are divided. On the basis of lamina (leaf blade) i.e. simple and compound leaves.

Compound leaves are further subdivided into pinnately and palmately compound leaves. 

 

 1. Simple leaf - Lamina is undivided, the incision donot touch the midrib
E.g. Banana leaf, guava leaf

 

                        Simple Leaf                                   Compound Leaf

2. Compound leaf - Leaf blade is completely divided forming number of leaflets.
E.g. Pea, palm leaves

(a.) Pinnately compound leaves - A number of leaflets are present on a common axis, the rachis, which represent the midrib of leaf in neem.

 

          Pinnately compound leaves                      Palmately compound leaves

                

(b.) Palmately compound leaves - the leaflets are attached at common point i.e. at the tip of petiole.
Eg. Silk cotton 

Modification of leaves

 Leaves are modified to perform function other than photosynthesis

 

1. Tendril - Tendril are thread like structure. Leaf tendrils exist in plants with weak stems.

The leaves modified to tendrils and helps in climbing & provide support to the plant. 

E.g. pea

2. Spines - Spines are needle like structure. They reduce water loss. Some plants modified their leaves into spines and act as defensive structure.

E.g. cactus

                                                                           

3. Store food - scale leaves in onion & garlic are fleshy & thick & store food & water.

4. Insectivorous leaves - In some plant, leaves are modified to catch & digest insect.

E.g.  Pitcher plant, Venus fly trap

 

Function of leaves 

 

1. Leaves collect carbon-dioxide, which is converts to sugars & oxygen by photosynthesis.

2. Stomata which is present in leaves help in removal of excess water from the plants.

3. Leaves store water & nutrients.

4. Some leaves modified to protect them from animals.