Structure of a Leaf:
The leaf mainly comprises three parts:
1. Leaf lamina/ leaf blade/ Epipodium
2. Petiole/ Mesopodium
3. Leaf base/ Hypopodium
1. Leaf-blade/ Lamina/ Epipodium:
2. Petiole/ Mesopodium:
3. Leaf base:
1. General characters & Structure of leaf
What is the axillary bud?
- The axillary bud is present in the axil of the lead, it later develops to form the branches.
What is meant by the term pulvinus?
- In leguminous plants, the leaf base becomes swollen up called the pulvinus.
Leaves are arranged in which order?
- Leaves are arranged in an acropetal order i.e older leaves are present at the base while newer leaves are found at the apex.
2. Types of Leaves
Give a differentiating feature leaf and leaflet?
- Both in simple & compound leaf, a bud is present in the axil of the petiole but it is absent in the leaflets of the compound leaf.
Solution: - The rachis is a common axis onto which leaflets are arranged.
- It represents the midrib of the leaf
- Example - neem.
What forms the basis of classifying leaves?
- On the basis of incisions of the lamina, leaves can be of two types: Simple leaf & Compound leaf.
- The leaf which has either a single entire lamina or if the lamina is incised, the incisions do not touch the midrib or petiole breaking it into a number of leaflets is called a simple leaf.
- The leaf in which the incisions touch the midrib or petiole such that it breaks the leaf into a number of leaflets is called a compound leaf.
Which type of venation is a characteristic of dicotyledonous plants?
- Reticulate venation is a characteristic of dicotyledonous plants.
- If the veins and veinlets are distributed irregularly and form a network such type of venation is termed reticulate venation.
Define alternate phyllotaxy?
- The type of arrangement in which only a single leaf is borne on each node of the stem in an alternate manner is called alternate phyllotaxy.
- Examples - Mustard, China rose, Sunflower.
What is the aim of phyllotaxy?
- The objective of phyllotaxy is to orient leaves in such a way that they receive the maximum sunlight for performing photosynthesis.