the origin of seeds in the land plants was achieved about 345 million years ago, in lineages recognised as anecestral to all more advanced vascular plants in

Options

A. Rhynia
B. Tracheophyte ancestor
C. Seed ferns
D. Conifers

Answer

To solve the question regarding the origin of seeds in land plants, we need to identify the group of plants where seed production first appeared around 345 million years ago. Here’s a step-by-step breakdown of the solution:

### Step-by-Step Solution:

1. **Understanding Seed-Producing Plants**:
- Seed-producing plants are categorized as **Spermatophytes**. They are further divided into two main groups: **Gymnosperms** and **Angiosperms**.

2. **Evaluating the Options**:
- The options provided include **Rhaenia**, **Tracheophytes**, **Conifers**, and **Seed Ferns**. We need to analyze each option to see which one is the correct answer.

3. **Analyzing Rhaenia**:
- Rhaenia is a genus of plants from the Devonian period. It is known to be a primitive plant and does not exhibit seed production. Therefore, this option is **incorrect**.

4. **Analyzing Tracheophytes**:
- Tracheophytes are vascular plants that possess well-differentiated vascular tissues (xylem and phloem). However, they do not specifically indicate the presence of seeds. Thus, this option is also **incorrect**.

5. **Analyzing Conifers**:
- Conifers are a group of gymnosperms that produce seeds. However, they are not the earliest group to exhibit seed production. Therefore, this option is **not the earliest** and can be considered **incorrect** in the context of the question.

6. **Analyzing Seed Ferns**:
- Seed ferns, which belong to the group of pteridophytes, are recognized as the precursors to seed habit due to their unique feature of **heterospory**. This characteristic is significant in the evolutionary history of plants and suggests that seed habit evolved from seed ferns. Hence, this option is **correct**.

7. **Conclusion**:
- Based on the analysis, the correct answer to the question is **Seed Ferns** (option C), as they represent the group of plants where the seed habit first appeared.