Which of the following is a n aquatic fern?

Options

A. Adiantum
B. Dryopteris
C. Salvinia
D. Equisetum

Explanation

To determine which of the following options is an aquatic fern, we will analyze each option provided:

1. **Adiantum**:
- Commonly known as the maidenhair fern.
- This genus consists of about 250 species.
- Prefers humus-rich, moist, well-drained sites, such as bottomland soils and vertical rock walls.
- Conclusion: Adiantum does not grow in aquatic environments; hence, it is **not** an aquatic fern.

2. **Dryopteris**:
- Commonly known as wood ferns, male ferns, or buckler ferns.
- Comprises about 300 to 400 species.
- Thrives in alkaline or acidic soils and prefers full shade or some sunlight.
- Conclusion: Dryopteris grows in soil and does not thrive in aquatic environments; therefore, it is **not** an aquatic fern.

3. **Salvinia**:
- Commonly known as water moss.
- This genus consists of aquatic ferns.
- The plant body features floating stems with two rows of large green leaves on the upper surface and modified leaf roots on the lower surface.
- Grows in aquatic habitats such as lakes and reservoirs.
- Conclusion: Salvinia is indeed an aquatic fern.

4. **Equisetum**:
- Commonly known as horsetail or snake grass.
- Considered a type of living fossil.
- Typically found in wet or swampy forests, open woodlands, or meadow areas.
- Conclusion: Equisetum grows in soil and is not classified as an aquatic fern.

After analyzing all the options, the correct answer is **Salvinia**, as it is the only option that is an aquatic fern.