To determine the inflorescence of grass, sedge, rice, and the family Gramineae, we can analyze the given options step by step.
### Step-by-Step Solution:
1. **Understanding Inflorescence Types**:
- Inflorescence refers to the arrangement of flowers on a plant. Different types include spike, thyrsus, spikelet, and raceme.
2. **Analyzing Option 1: Spike**:
- A spike is characterized by having a peduncle (the stalk of the flower cluster) that bears bisexual and sessile (stalkless) flowers. This is a type of racemose inflorescence. An example of a plant with a spike is Achiranthus.
3. **Analyzing Option 2: Thyrsus**:
- A thyrsus is a complex inflorescence where several simos (similar) clusters of flowers are borne acropetally (from the base to the tip) on an unlimited axis. An example of this type is grapevine.
4. **Analyzing Option 3: Spikelet**:
- A spikelet is a small and specialized spike. In spikelets, flowers are produced in the axils of fertile bracts known as lemma. This type of inflorescence is characteristic of grasses, sedges, rice, and wheat, which belong to the family Gramineae.
5. **Analyzing Option 4: Raceme**:
- A raceme has a peduncle with bisexual and pedicellate (stalked) flowers arranged acropetally. An example of a plant with a raceme is Raphanus (radish).
6. **Conclusion**:
- Given that grass, sedge, and rice belong to the family Gramineae, the correct answer for their inflorescence type is **spikelet**. This is because spikelets are specifically adapted for these plants, allowing them to produce flowers in a compact and efficient manner.
### Final Answer:
The inflorescence of grass, sedge, rice, and the family Gramineae is **spikelet**.
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