Young Root of Broad Bean Under the Microscope
Young Root of Broad Bean (Cross Section), Vicia faba
This is a cross section of a young broad bean root stained with fast green. It shows the classic tissue layers of a young dicot root.
This cross section of a young broad bean (Vicia faba) root demonstrates the classical primary anatomy of a dicotyledonous root system. Surrounding the exterior is a single-layered epidermis (epiblem), enclosing an extensive parenchymatous cortex composed of large, thin-walled storage cells with intercellular air spaces. The innermost layer of the cortex forms a distinct endodermis surrounding the central stele. Within the vascular cylinder, alternating radial strands of primary xylem and primary phloem are clearly delineated, showcasing characteristic exarch development where protoxylem elements lie toward the periphery and metaxylem vessels extend toward the center, surrounding a well-defined parenchymatous pith.
What to look for
- Epidermis: The outer layer of cells, which may have root hairs.
- Cortex: A wide zone of large, round cells with small air spaces between them.
- Endodermis: A single ring of cells at the inner edge of the cortex.
- Pericycle: A thin layer just inside the endodermis.
- Xylem and phloem: Groups of xylem and phloem that alternate around the center of the root.
- Pith: Small central area of thin-walled cells, in the middle of the vascular tissue.
At each magnification
Low power (about 4x)
A round section with a wide cortex and a small central core.
Medium power (about 10x)
The endodermis ring and the pattern of xylem and phloem inside it.
High power (about 40x)
Thick-walled xylem vessels and the small cells of the endodermis.
Questions and answers
What are the parts of a root cross section?
From the outside in, a root has an epidermis, a wide cortex, a ring of endodermis, a pericycle, and a central core of xylem and phloem. In a young dicot root, xylem and phloem alternate around the center.
Where do side roots come from?
Side roots start in the pericycle, the layer just inside the endodermis. They grow outward through the cortex and break through the epidermis.
- Category
- Botany & Plants
- Scan magnification
- 20x
- Stain
- Fast Green
- Tags
- young root of broad bean, Vicia faba, broad bean root, dicot root cross section, plant anatomy, vascular cylinder
Viewing this slide in class
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