Questions and Answers
What is a modified stem that serves as a photosynthetic and storage organ?
Thorny stems are derived from reduced leaves.
False
What is the function of a stolon/runner?
A stolon/runner is a vegetative shoot that spreads along the surface of the ground and roots at the nodes, giving rise to new plantlets.
A _______________________ is a sharp outgrowth from the epidermis of a stem.
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What type of stem modification has several distinct nodes?
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Stolons/Runners are underground stems.
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Match the following modified stems with their descriptions:
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A _______________________ is a modified stem that grows along the surface of the ground and roots at the nodes.
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Which of the following is an example of a modified stem?
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What is the main difference between a thorny stem and a prickly stem?
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Study Notes
Root Structure
- Striga hermonthica is a parasite that attacks rice roots
- The haustorium of S. hermonthica penetrates the rice root, with the parasite xylem (Px) and host xylem (Hx) visible in a cross-section
- The hyaline body (HB) and cortical parenchyma (COR) are also present in the interface between the haustorium and the host root
- Tomato roots exhibit secondary growth
Stem Structure
- Aerial stems are above-ground stems that grow upwards
- Underground stems are below-ground stems that grow horizontally
- Stems can be modified to perform specialized functions, such as:
- Stem tendrils: slender, thread-like structures that help in climbing and support
- Twining stems: stems that wrap around a support in a helical manner to climb
- Rhizomes: underground stems that grow horizontally and have nodes, buds, or scale-like leaves
- Corms: short, swollen underground stems
- Bulbs: underground stems with a bud enclosed by fleshy scale leaves and/or leaf bases
- Tubers: thickened branches of underground stems with leaves/leaf scars and axillary buds
Modified Stems
- Cladodes: green, flattened or cylindrical, thick, succulent modified main stems that serve as photosynthetic and storage organs
- Hooks: plant stems modified to form hooks
- Prickles: sharp outgrowths from the epidermis of a stem
- Thorny stems: short, pointy woody structures derived from reduced branches
- Stolons/Runners: vegetative shoots that spread along the surface of the ground and root at the nodes, giving rise to new plantlets
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Description
This quiz covers the root structure of rice plants affected by the parasitic plant Striga hermonthica, including the anatomy of the haustorium and its interaction with the host root.