Gymnosperms

Let's evaluate each statement to determine the correct answer:

1. Statement 1: Ovules are not enclosed by ovary wall in gymnosperms.
   • This statement is correct. In gymnosperms, the ovules are exposed or naked, meaning they are not enclosed within an ovary wall. Unlike angiosperms where ovules are enclosed by the ovary, gymnosperms have open ovules located on the surface of cone scales.
2. Statement 2: Horsetails are gymnosperms.
   • This statement is incorrect. Horsetails belong to the division Pteridophyta and are classified as seedless vascular plants. Gymnosperms, on the other hand, are seed-producing plants like conifers.
3. Statement 3: Selaginella is heterosporous, while Salvinia is homosporous.
   • This statement is incorrect. Both Selaginella and Salvinia are heterosporous, meaning they produce two different types of spores: microspores and megaspores.
4. Statement 4: Stems are usually unbranched in both Cycas and Cedrus.
   • This statement is incorrect. Cycas typically has unbranched stems, but Cedrus (cedar trees) are known for their branching stems.

Based on the evaluation above, the correct answer is: Ovules are not enclosed by ovary wall in gymnosperms.