Cotton Root Cross Section Under the Microscope
Cotton Root (Cross Section), Gossypium hirsutum
This is a cross section of a young cotton root stained with safranin and fast green. It shows the layers of a dicot root, from the outer skin to the vascular core in the center.
This is a cross section of a cotton root (Gossypium hirsutum), stained with safranin and fast green. The center is filled with large, round xylem vessels with red walls, tubes that carry water and minerals up from the root. Around the xylem are smaller green cells, including the phloem, which carries sugar made in the leaves. The outer rings of larger, thin-walled cells form the cortex, which stores food and passes water inward. The red and green stains make it easy to tell the woody, water-carrying cells from the softer tissue around them.
What to look for
- Epidermis: The outer layer of small cells around the edge of the root.
- Cortex: A wide zone of large, round, thin-walled cells, stained green, between the epidermis and the center.
- Endodermis: A single ring of cells at the inner edge of the cortex that controls what enters the vascular core.
- Pericycle: A thin layer just inside the endodermis, where side roots begin.
- Xylem: Thick-walled cells stained red in the center, often arranged in a star or cross shape.
- Phloem: Small green-stained cell groups sitting between the arms of the xylem.
Questions and answers
What does a dicot root cross section look like under a microscope?
A dicot root has an epidermis, a wide cortex, a ring of endodermis, and a central core where xylem forms a star or cross shape with phloem between the arms. With safranin and fast green, the xylem is red and most other tissue is green.
What is the endodermis in a root?
The endodermis is a single layer of cells around the vascular core. Its walls have a waterproof band called the Casparian strip, which forces water and minerals to pass through the cells, so the root can control what it takes in.
How is a root cross section different from a stem cross section?
In a dicot root, xylem and phloem alternate around the center, with xylem often in a star shape. In a dicot stem, xylem and phloem sit together in bundles arranged in a ring around a central pith.
- Category
- Botany & Plants
- Scan magnification
- 20x
- Stain
- Safranin and Fast Green
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