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2.4

Major VersionM

by Manikandan S

Introduction

A leaf has 2 parts namely the leaf blade and the stalk. The leaf blade consists of the apex, veins, midrib, margin and base. The arrangement of veins in a leaf blade is known as venation. The veins help in the transport of food and water.

In this TACtivity, observe a leaf lamina and its different parts (apex, margin, veins, veinlets), using your own DIY microscope.

Video Overview

    • Be careful while handling the scissors and any other sharp tool.

  1. DIY Microscope is a prerequisite TACtivity that has to be completed before commencing this TACtivity. The DIY Microscope is created with two glass beads of 4.5mm and 2.5mm diameter offering a 40X / 100X magnification.
    • DIY Microscope is a prerequisite TACtivity that has to be completed before commencing this TACtivity. The DIY Microscope is created with two glass beads of 4.5mm and 2.5mm diameter offering a 40X / 100X magnification.

    • Go to DIY Microscope to complete the TACtivity.

  2. Carefully remove the transparent layer from both the sides of the slide. Wipe the slide with tissue paper.
    • Carefully remove the transparent layer from both the sides of the slide.

    • Wipe the slide with tissue paper.

  3. Select a small, thin and fresh leaf to observe the venation pattern on it. Leaves have two surfaces - smooth (top) and rough (bottom). The rough surface is placed touching the slide (indicated with a blue arrow). Secure the leaf on the slide with clear tape.
    • Select a small, thin and fresh leaf to observe the venation pattern on it.

    • Leaves have two surfaces - smooth (top) and rough (bottom). The rough surface is placed touching the slide (indicated with a blue arrow).

    • Secure the leaf on the slide with clear tape.

  4. View the leaf venation using your  4.5 mm bead of DIY Microscope. Ensure that there is a bright light source behind the slide. Observe the veins, veinlets, midrib and other parts of the leaf using both beads of the microscope.
    • View the leaf venation using your 4.5 mm bead of DIY Microscope. Ensure that there is a bright light source behind the slide.

    • Observe the veins, veinlets, midrib and other parts of the leaf using both beads of the microscope.

    • Refer to the graphical representation in second picture to compare different parts.

  5. Notice the origin of the veins in the midrib. Veins originate from the mid rib at different position. The apex region observed using the microscope. The margins, as seen through the microscope.
    • Notice the origin of the veins in the midrib. Veins originate from the mid rib at different position.

    • The apex region observed using the microscope.

    • The margins, as seen through the microscope.

  6. Select a long, thin and fresh leaf and cut a small portion of the following separately: Apex Margin
    • Select a long, thin and fresh leaf and cut a small portion of the following separately:

    • Apex

    • Margin

    • Central portion

  7. Stick the leaf samples on a slide (with smooth side up) with transparent tape and observe them  using your microscope. Stick the leaf samples on a slide (with smooth side up) with transparent tape and observe them  using your microscope.
    • Stick the leaf samples on a slide (with smooth side up) with transparent tape and observe them using your microscope.

  8. Apex with hairy texture as observed under the microscope. The origin of veins in the midrib. The margin with a wavy shape and hair on it.
    • Apex with hairy texture as observed under the microscope.

    • The origin of veins in the midrib.

    • The margin with a wavy shape and hair on it.

  9. Take a blade of grass (or any other monocot leaf) and  cut a small portion of its apex. Also cut a 1 cm section from the middle of the leaf. Stick the sample onto the slide with a piece of transparent tape. Make sure the leaf is secure from all sides.
    • Take a blade of grass (or any other monocot leaf) and cut a small portion of its apex.

    • Also cut a 1 cm section from the middle of the leaf.

    • Stick the sample onto the slide with a piece of transparent tape. Make sure the leaf is secure from all sides.

  10. Look for the origin of the venation and midrib (if any). Notice the margin which has a hairy texture. Refer to the graphical representation in third picture to  compare different parts of the grass blade.
    • Look for the origin of the venation and midrib (if any).

    • Notice the margin which has a hairy texture.

    • Refer to the graphical representation in third picture to compare different parts of the grass blade.

    • Unclear image -

    • Ensure that the side of the slide with the object mounted is in contact with the microscope.

    • Move the microscope bead slightly up or down using the straw till you get the focus (sharp image).

    • Patterns on the leaf are not clear -

    • Make sure bright light (phone light, torch or bright daylight) is illuminating the slide from behind; do not point towards the Sun.

    • Choose a thin, small and fresh leaf.

  11. Try preparing a slide with a dried/yellow leaf and observe the venation pattern. Thin veins in thick midrib Thin veins running parallel to each other
    • Try preparing a slide with a dried/yellow leaf and observe the venation pattern.

    • Thin veins in thick midrib

    • Thin veins running parallel to each other

    • Leaf with wavy margin.

    • For more variations, Go to Microscope - Leaf Venation (Variations).

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