Sunflower Stem Cross Section Under the Microscope
Sunflower Stem (Cross Section), Helianthus annuus
This is a cross section of a young sunflower stem stained with fast green. It is the textbook example of a dicot stem, with vascular bundles arranged in a ring around a central pith.
This cross section of a young sunflower (Helianthus annuus) stem is stained with Fast Green. It shows the classic dicot stem plan: a ring of vascular bundles around a large central pith of big, thin-walled cells. Each bundle holds xylem, thick-walled tubes that carry water, on the side facing the center, and phloem, which carries sugars, on the outer side. Between the bundles and the thin outer epidermis lies the cortex, a few layers of packed cells. Students can compare this ring of bundles with the scattered bundles of a corn stem.
Labeled sunflower stem cross section under the microscope
- Epidermis: Single outer layer of cells
- Cortex: Packed cells between the epidermis and the bundles
- Bundle cap: Thick-walled fibers on the outer side of a bundle
- Xylem: Water-carrying cells on the inner side of a bundle
- Vascular bundles in a ring: Bundles form one ring around the pith
- Pith: Large thin-walled cells in the center
What to look for
- Epidermis: A single outer layer of cells.
- Cortex: A narrow zone of supporting and storage cells under the epidermis, including thick-cornered collenchyma.
- Vascular bundles: Wedge-shaped bundles arranged in a ring.
- Xylem, cambium, and phloem: Xylem on the inner side of each bundle, phloem on the outer side, and a thin cambium between them.
- Bundle caps: Clusters of thick-walled fiber cells capping the outer side of each bundle.
- Pith: Large, thin-walled cells filling the center of the stem.
Questions and answers
What does a dicot stem cross section look like under a microscope?
A dicot stem like sunflower has an epidermis, a cortex, a ring of vascular bundles, and a central pith. In each bundle, xylem faces the center, phloem faces outward, and a thin cambium lies between them.
How is a sunflower stem different from a corn stem?
A sunflower stem is a dicot stem, with its vascular bundles in one ring around a pith. A corn stem is a monocot stem, with its bundles scattered throughout.
Compare it
- Category
- Botany & Plants
- Scan magnification
- 20x
- Stain
- Fast Green
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