Which one does not exhibit seed dormancy ?

Options

A. Rhizophora
B. Xanthium
C. Phaseolus
D. Cassia

Answer

To determine which plant does not exhibit seed dormancy among Rhizophora, Xanthium, Cassiolus, and Cassia, we can analyze the characteristics of each plant regarding their seed behavior.

### Step-by-Step Solution:

1. **Understand Seed Dormancy**: Seed dormancy refers to a state in which seeds are inactive and do not germinate even under favorable conditions. This is a survival mechanism for many plants.

2. **Identify the Plants**: The plants in question are:
- Rhizophora
- Xanthium
- Cassiolus
- Cassia

3. **Analyze Rhizophora**:
- Rhizophora is a type of mangrove tree known for its viviparous nature, meaning its seeds germinate while still attached to the parent plant.
- The propagules (young plants) develop directly from the seed and can root in the soil before detaching from the parent tree.
- This indicates that Rhizophora does not have a dormant seed stage; instead, it grows directly into a plant.

4. **Analyze Other Plants**:
- **Xanthium**: This plant typically has seeds that can enter a dormant state.
- **Cassiolus**: Similar to Xanthium, it also exhibits seed dormancy.
- **Cassia**: This plant is known to have seeds that can remain dormant until conditions are favorable for germination.

5. **Conclusion**: Based on the analysis, Rhizophora is the only plant among the options that does not exhibit seed dormancy. Its seeds germinate while still attached to the parent plant, leading to the formation of new trees without entering a dormant stage.

### Final Answer:
**Rhizophora does not exhibit seed dormancy.**