Q1.
Look at the leaves of different plants collected by you, during the nature walk. Do you notice any variation in the shape and structure of these leaves?
Answer
Yes — a great deal of variation. Hold each leaf up against the light and the differences become obvious.
| What varies | What you see |
|---|---|
| Shape | Long and narrow in grass; broad and pointed in gudhal; heart-shaped in money plant; needle-like in pine |
| Size | A tiny tulsi leaf beside a banana leaf a metre long |
| Margin (edge) | Smooth in mango; toothed in tulsi and rose |
| Surface | Smooth and shiny in neem; rough and hairy in some others |
| Number of parts | A single blade in mango; many small leaflets on one stalk in neem and imli |
| Veins | Thin lines running through the leaf — in a net-like pattern in gudhal, side by side in banana and grass |
Why the last row is the important one: shape and size change even between two leaves of the same plant — an old leaf is bigger than a new one. But the pattern of veins never changes within a plant. A feature that stays the same is a reliable basis for grouping, so it is venation that the chapter takes up next.