Pumpkin Stem Cross Section Under the Microscope
Pumpkin Stem (Cross Section), Cucurbita pepo
This is a cross section of a pumpkin stem stained with fast green. Pumpkin stems have unusual vascular bundles with phloem on both sides of the xylem, making it a popular slide for studying plant transport tissues.
This is a cross section of a pumpkin stem (Cucurbita pepo), stained green with fast green. The stem has a ridged, five-sided outline and a hollow center where the pith has broken down. Around the hollow sit two rings of vascular bundles, the strands that carry water and food, and each holds a few very large, round xylem vessels that carry water up from the roots. Pumpkin bundles are bicollateral, which means they have phloem, the food-carrying tissue, on both the inner and outer side of the xylem. Outside the bundles are layers of cortex cells that support and store, covered by a thin epidermis.
What to look for
- Epidermis: The outer layer of cells around the ridged edge of the stem.
- Cortex: Supporting and storage cells under the epidermis, including thick-cornered collenchyma.
- Vascular bundles: Large bundles arranged in rings around a hollow or loose center.
- Xylem vessels: Very large, open, round vessels in the middle of each bundle.
- Outer and inner phloem: Phloem on both the outer and inner sides of the xylem in each bundle.
- Sieve tubes: Large phloem cells in which sieve plates can sometimes be seen.
Questions and answers
What is a bicollateral vascular bundle?
A bicollateral bundle has phloem on both sides of the xylem, one on the outside and one on the inside. Pumpkin and other squash stems are the classic example.
Why use a pumpkin stem to study phloem?
Pumpkin phloem has very large sieve tubes, so the sieve plates between them are easier to see than in most plants. The xylem vessels are also large and easy to spot.
Compare it
- Category
- Botany & Plants
- Scan magnification
- 20x
- Stain
- Fast Green
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