Comparative Plant Anatomy: Monocot vs. Dicot Lab

An online microscope lab for middle school and high school science on StudyScope. Students work through 15 real prepared microscope slides in order: Corn Stem (Cross Section), Sunflower Stem (Cross Section), Tilia Stem (Cross Section), Pumpkin Stem (Cross Section), Rice Stem (Cross Section), Wheat Stem (Cross Section) and 9 more.

Students learn to tell monocots from dicots by looking inside stems, roots, and leaves. Each unit opens with clear reference slides, then asks students to classify the next slides on their own and defend the call with evidence. Section titles name the plant but not its group, so the answer has to come from the slide. You drive the slides; students follow on their own screens and can pan and zoom. Have students keep a table with a row each for stem, root, and leaf, and a column each for monocot and dicot. About 50–60 minutes. To shorten it, skip pumpkin, wheat, radish, and sunflower leaf.

Grade level
Middle school and high school
Time
55 minutes
Subject
Botany & Plants
Slides
15
NGSS
MS-LS1-3, HS-LS1-2

NGSS alignment

Lab steps

  1. Stems: corn, a monocot

    Slide: Corn Stem (Cross Section)

    • This is a corn stem, cut across. Each small oval is a vascular bundle: a cluster of tubes that carries water and food through the plant. Describe how the bundles are spread across the stem. Do they form a pattern?
    • Zoom in on one bundle. The big round openings are xylem vessels, which carry water up from the roots. The patch of small cells beside them is phloem, which carries sugar. Many people say a corn bundle looks like a face. Sketch one and label the xylem and phloem.

  2. Stems: sunflower, a dicot

    Slide: Sunflower Stem (Cross Section)

    • Now a sunflower stem. Compare it with the corn stem. How are the vascular bundles arranged here? What fills the center?
    • Zoom in on one bundle. The xylem is on the side facing the center of the stem. The phloem is on the side facing out. Between them is a thin band of small cells called cambium, which can make new cells so the stem grows wider. Add the dicot stem to your table: how the bundles are arranged, what is in the center, and whether it has cambium.

  3. Stems, your call: basswood

    Slide: Tilia Stem (Cross Section)

    • Your call: is this basswood stem a monocot or a dicot? Look at the big picture first: what is in the center, and how is the tissue around it arranged? Write your answer and one piece of evidence.
    • Zoom in on the wide ring around the center. This is wood, made by a ring of cambium adding new cells season after season. Look for thin lines running outward like the spokes of a wheel. Why couldn't a corn stem ever grow wood like this?

  4. Stems, your call: pumpkin

    Slide: Pumpkin Stem (Cross Section)

    • Your call: pumpkin stem. Is it a monocot or a dicot? Look at how the bundles are arranged, and record your evidence.
    • Zoom in on one of the large bundles. The huge round openings are xylem vessels. Pumpkin plants grow fast and make heavy fruit. Why might they need extra-wide water pipes?

  5. Stems, your call: rice

    Slide: Rice Stem (Cross Section)

    • Your call: rice stem. Careful, this one is tricky. Look at the center and at how the bundles are arranged. Monocot or dicot? Write down your evidence before the next step.
    • Zoom in on the wall of the stem. Compare one bundle with the corn and sunflower bundles: which one does it look more like? What might the large holes between the bundles be for? (Hint: rice grows standing in water.)

  6. Stems, your call: wheat

    Slide: Wheat Stem (Cross Section)

    • Your call: wheat stem. Is it more like rice or more like sunflower? Give two pieces of evidence. Then think about this: a hollow tube is strong but light. Why might that help a tall, thin grass?

  7. Roots: corn root tip, a monocot

    Slide: Zea Root Tip (Longitudinal Section)

    • Now roots. This corn root (a monocot) is cut lengthwise. Find the root cap at the tip. Just behind it, the cells are tiny and packed together; this is where new cells are made. Farther back, the cells get longer. Why does a root need a cap?
    • Look down the middle of the root. A column of long, narrow cells runs through the center. This is the root's vascular core. In stems, the bundles sat out toward the edge. Why might a root keep its pipes in the center? (Think about wind tugging on the plant above.)

  8. Roots: young broad bean, a dicot

    Slide: Young Root of Broad Bean (Cross Section)

    • Now a young broad bean root (a dicot), cut across. Find the three main zones: the thin outer skin, the wide cortex of large round cells, and the small, dense core in the center. How is this layout different from the stems we looked at?
    • Zoom in on the core. A ring of small cells, the endodermis, wraps around it like a fence. Everything that enters the core has to pass through this ring. What might the plant gain by having a checkpoint here?

  9. Roots: cotton, an older dicot root

    Slide: Cotton Root (Cross Section)

    • This cotton root is a dicot, older than the bean root. The red-ringed circles in the center are xylem vessels. Is there pith in the middle, like the sunflower stem had, or is the center solid xylem? Add the dicot root to your table.

  10. Roots: radish, a root that grew thick

    Slide: Radish Root (Cross Section)

    • This is a radish, the part people eat. It's a root that grew thick. Look for rows of xylem vessels spreading out from the center like spokes. Which slide from earlier today also grew thicker by adding new tissue in rings?
    • Monocot roots, like grass roots, stay thin and stringy. Dicot roots, like this radish, can grow thick. What tissue do dicots have that lets them grow wider? Where else did you see it today?

  11. Leaves: Tradescantia surface, a monocot

    Slide: Lower Epidermis of Tradescantia reflexa Leaf (Whole Mount)

    • Now leaves. This is a thin peel from the underside of a Tradescantia leaf (a monocot), seen from above. Describe the shape of the cells and how they are arranged.
    • Each box marks a stoma: a tiny pore between two guard cells that lets gases in and out of the leaf. Find at least five more. Which way do they point? Are they lined up or scattered?

  12. Leaves: broad bean surface, a dicot

    Slide: Lower Epidermis of Broad Bean Leaf (Whole Mount)

    • Now a peel from a broad bean leaf (a dicot). Compare it with Tradescantia. What shape are the cells? Are the stomata lined up or scattered? Add both leaf surfaces to your table.
    • Zoom out and look at the dark bands crossing the peel. These are veins under the surface. Do they run side by side, or do they branch? How does that compare with the veins on a blade of grass?

  13. Leaves: inside a cotton leaf, a dicot

    Slide: Cotton Leaf (Cross Section)

    • Now inside a leaf. This cotton leaf (a dicot) is cut across. Find the row of tall, tightly packed palisade cells along one side, where most photosynthesis happens. Then find the looser cells with air spaces on the other side. Why might the cells near the stomata be loose, with gaps between them?
    • Find the big vein, the midrib. In a dicot leaf, one main vein branches into smaller and smaller veins, like the ones you saw in the broad bean peel. Add the inside of a dicot leaf to your table.

  14. Leaves, your call: lily

    Slide: Lily Leaf (Cross Section)

    • Your call: lily leaf. Scan across the whole leaf and count the veins. Then zoom in on the cells between them: is there a clear row of tall palisade cells like cotton had? Monocot or dicot? What is your evidence?

  15. Leaves, your call: sunflower

    Slide: Sunflower Leaf (Cross Section)

    • Your call: sunflower leaf. You saw a sunflower stem earlier today. Does the leaf agree with it? Find the palisade layer and the veins, and give your evidence. Bonus: what might the hairs sticking out of the surface be for?

  16. Wrap-up: monocot vs. dicot summary

    • Finish your table. For stems, roots, and leaves, write one monocot feature and one dicot feature. Then pick one feature and explain how it helps the plant move water, stand up, or exchange gases.

Slides used in this lab

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