infloresecence consisting of sessile bisexual flowers arranged acropetally on an elongated axis is

Options

A. spadix
B. catkin
C. Raceme
D. spike

Answer

To solve the question regarding the type of inflorescence that consists of sessile bisexual flowers arranged acropetally on an elongated axis, we can follow these steps:

### Step 1: Understand the Key Terms
- **Inflorescence**: This refers to the arrangement of flowers on a plant.
- **Sessile Flowers**: These are flowers that do not have a stalk (pedicel) and are directly attached to the main axis.
- **Bisexual Flowers**: These flowers contain both male (stamens) and female (pistils) reproductive structures.
- **Acropetal Arrangement**: This means that the flowers are arranged such that the younger flowers are at the top and the older ones are at the bottom.

### Step 2: Analyze the Options
- **Catkin**: This is a type of inflorescence that typically consists of unisexual flowers and is often compact. Therefore, it does not fit the description.
- **Spadix**: This is characterized by a fleshy axis and often has unisexual flowers as well, so it is also not the correct answer.
- **Raceme**: This is a type of inflorescence where the main axis continues to grow, and flowers are borne on pedicels. However, it can also include variations like spikes.
- **Spike**: This is an elongated inflorescence where flowers are sessile and arranged acropetally.

### Step 3: Identify the Correct Inflorescence
From the analysis, we can conclude that the correct answer is **Spike**. In a spike, the flowers are sessile, bisexual, and arranged acropetally on an elongated axis.

### Step 4: Provide Examples
Examples of spikes include:
- **Calistemon** (Bottlebrush)
- **Amaranth**

### Conclusion
The type of inflorescence consisting of sessile bisexual flowers arranged acropetally on an elongated axis is a **Spike**.

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