Step 1: Ask students to collect leaves with different shapes size and venation. Give them the chart on attached above for their reference.
Step 2: let them dry these leaves collected for two-three days by pressing it in thier books.
Step3: Ask them to now segregate their collection on the following basis :
Types of venation- 1. Reticulate Venation:
When the veins are irregularly distributed to form a channel, it is known as Reticulate Venation.
It is the characteristic feature seen in dicots.
They are of two types:
a) Unicostate or Pinnate Reticulate:
Leaf having a single main mid-rib.
Example: Hibiscus, Mango
b) Multicostate or Palmate Reticulate:
Having two or more mid-ribs arising from a single point.
They are further divided as:
i) Multicostate convergent:
Many mid-ribs in a curved fashion from base of blade to its apex.
Example: Zizyphus (Beri)
ii) Multicostate divergent:
Many mid-ribs arise at the base of the leaf and then diverge from one another towards the margin.
Example: Papaya, Cucurbita
2. Parallel Venation: Veins are parallel and do not form a network.
They are of two types:
a) Unicostate or Pinnate parallel:
Lamina has a single prominent midrib from which lateral veins arise which run towards the margin.
Example: Canna, Banana
b) Multicostate or Palmate parallel:
Several leaves run parallel to each other.
They are further divided as:
i) Multicostate convergent:
Principal veins appear from the base of the lamina and converge at the apex.
Example: Bamboo
ii) Multicostate divergent:
Main veins appear from the base of the lamina and converge at the apex.
Example: Fan palm
Step 4: Along with the venation and their types students should mark the following for each leaf they have collected :
a) Margins
b) Shape
c) Leaf Apex
d) Arrangement of the leaf
e) Arrangement on stem
3. Furcate Venation: Dichotomous branched veins. Also known as forked venation.
Example: Nephrolepis (Fern)
