What characteristic distinguishes giant water fern from regular water fern?

The characteristic that distinguishes giant water fern from regular water fern is that the hairs on the upper leaf surface are fused at the top. This feature is significant in identifying giant water fern, as it reflects the unique morphological adaptations of the plant. The fusion of the hairs can play a role in the plant’s respiration and moisture retention, setting it apart from other species in the same family that do not exhibit this trait.

In contrast to this distinctive feature, the root-like leaves, closely overlapping leaves, and paired rounded leaves do not accurately represent the differences between giant and regular water fern. While these characteristics may be present in various aquatic plants, they do not specifically define the giant water fern's identity. Thus, the fused hairs at the top of the leaves serve as a key identifier for recognizing and distinguishing this species in aquatic ecosystems.