INTRODUCTION OF LEAVES AND MODIFICATIONS OF LEAVES

MODIFIED LEAVES SUCH AS LEAF TENDRILS,HOOKS,PITCHER,BLADDER AND SPINY LEAVES

1. Topic :Modifications of leaf Present by : HASNAIN SARWAR Roll No.: “4128”

2. What is leaf? d r . aarif CHARACTERISTICS OF LEAF : Leaf is a thin, expanded, green structure. The green colour of the leaf is due to the presence of chlorophyll pigmen . It is borne on the stem at the node. An axillary bud is often present in the axil of each leaf. It has limited growth. They also carry the process of transpiration. Leaves are green flat structures borne on the stem or on the branches.

3. Modifications of leaves(types) Leaf tendril Leaf spines Leaf bladder Leaf pitcher Phyllodes

4. What is modification of leaf ? The primary function of leaf are photosynthesis and transpiration But in many plants the leaves are modified to perform some additional functions these are called modified leaves.

5. MODIFICATIONS OF LEAVES: d r . aarif 1- LEAF TENDRILS : - In certain plants having weak stem , entire leaf or a part of it gets modified into an elongated , thin, cylindrical, coiled , wiry , sensitive structure known as tendril. These tendrils help the plant to climb up on some support . In wild pea (Lathyrus), entire leaf is tendrillar, in sweet pea (Pisum sativum) terminal leaflets are tendrillar, in Gloriosa only the leaf apex modifies into tendril, and - in Smilax, stipules become tendrillar.

6. MODIFICATIONS OF LEAVES: d r . aarif 2- LEAF SPINES: . Leaves of certain plants become wholly or partially modified for defensive purpose into sharp, pointed structures known as spines - Sometimes only a part of leaf such as stipules , get modified into spines , to protect plants from grazing animals , e.g., Zizyphus and Acacia. - In barberry the leaf itself becomes modified into a spine; while the leaves of the axillary bud are normal.

7. MODIFICATIONS OF LEAVES: d r . aarif 3- LEAF HOOKS : In this the leaves are modified into hooks and help the plant to climb the support. In Bignonia unguis- cati (Cat's nail), the terminal three leaflets get modified into three stiff curved & pointed hooks which look like cat's nail . - They cling to bark of tree ( support ) and help the plant for climbing

8. Mor MODIFICATAIONS OF LEAVES phology of Leaf d r . aarif 4-PHYLLODE : In some plants, petiole becomes flat , green and leaf like and performs photo synthesis. This is known as phyllode . There are about 300 species of Australian Acacia, all showing the phyllode .

9. 5 -Insect Catching Leaves In insectivorous plants, the leaves are especially adapted to catch and digest insects to fulfil their nitrogen requirement. Some of the adaptations are given below . Leaf pitcher: n the pitcher plant (Nepenthes) the leaf becomes modified into a pitcher. There is a slender stalk which coils like a tendril holding the pitcher vertical and the basal portion is flattened like a leaf. The pitcher is provided with a lid which covers the mouth. The function of the pitcher is to capture and digest insects.

10. Leaf bladder: Utricularia is another insectivorous plant which grows in water. It bears highly dissected submerged leaves. Some of the segments of the leaf are modified into bladders. These bladders serve as floats for the aquatic plants and for trapping the insects .