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 answer the question regarding the origin of seeds in land plants, we need to analyze the options provided and determine which lineage is recognized as ancestral to all more advanced vascular plants.

### Step-by-Step Solution:

1. **Understanding the Context**: The question states that the origin of seeds in land plants occurred about 345 million years ago. This is a significant evolutionary milestone in the development of vascular plants.

2. **Identifying the Options**: The options given are:
- Rhinia
- Tracheophyte Ancestors
- Seed Ferns
- Conifers

3. **Evaluating Rhinia**:
- Rhinia is a plant from the Paleozoic era, primarily associated with marine environments. Since seeds had not yet evolved during this time, Rhinia cannot be the correct answer.

4. **Evaluating Tracheophyte Ancestors**:
- Tracheophytes are vascular plants that have differentiated xylem and phloem. However, while they represent an important evolutionary step, they do not specifically indicate the presence of seeds. Thus, this option is also incorrect.

5. **Evaluating Seed Ferns**:
- Seed ferns, or pteridophytes, reproduce via spores but have characteristics that are similar to seed-bearing plants. They produce megaspores and microspores, which are precursors to seeds. This lineage is crucial in understanding the evolution of seed-bearing plants, making this the most likely correct option.

6. **Evaluating Conifers**:
- Conifers are a group of gymnosperms that produce seeds but are not the ancestral lineage from which all advanced vascular plants evolved. They are adapted to specific environments and do not represent the origin of seeds in the broader context of plant evolution.

7. **Conclusion**: Based on the analysis, the correct answer is **Seed Ferns**, as they represent a significant evolutionary step towards the development of seed-bearing plants.

### Final Answer:
The origin of seeds in land plants was achieved about 345 million years ago in lineages recognized as ancestral to all more advanced vascular plants in **Seed Ferns**.

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