To test the presence of starch in leaves, you use the classic iodine leaf- starch test done in school labs.

Quick Scoop: Core Idea

You boil a green leaf, remove its green color with alcohol, then drop iodine solution on it.
If starch is present, the leaf (or parts of it) turns blue‑black.

Materials You Need

  • A fresh green leaf (from a plant kept in light)
  • Beaker with water
  • Test tube or boiling tube
  • Ethanol (alcohol)
  • Dropper
  • Iodine solution
  • Forceps
  • Heat source (water bath, kettle or similar)
  • White tile or Petri dish

Step‑by‑Step Procedure

  1. Boil the leaf in water
    • Place the leaf in hot or gently boiling water for a few minutes.
    • This kills the leaf and stops further chemical reactions.
  2. Boil the leaf in ethanol
    • Transfer the leaf into a test tube containing ethanol.
    • Put the tube in a hot water bath until the leaf loses its green color (chlorophyll is removed).
    • This decolorization makes any color change with iodine easy to see and also softens the leaf.
  3. Rinse the leaf in water
    • Take the now pale/brittle leaf out and rinse it briefly in warm or cold water.
    • This re‑softens the leaf so it can lie flat and not crumble.
  4. Place on a white tile
    • Spread the leaf out flat on a white tile or Petri dish so you can clearly observe color changes.
  5. Add iodine solution
    • Using a dropper, cover the leaf with iodine solution.
  6. Observe the color change
    • If starch is present, the leaf (or parts of it) turns blue‑black.
    • Areas without starch stay yellow‑brown (the original iodine color).

What This Shows

  • Blue‑black color = starch is present in that part of the leaf.
  • This indicates that photosynthesis produced glucose, which the plant stored as starch in those cells.

One‑line Answer (Exam Style)

Boil a green leaf in water, then in ethanol to remove chlorophyll, rinse, spread it on a white tile, add iodine solution; if starch is present the leaf turns blue‑black.