What characteristic is notable in Salvinia species?

The notable characteristic in Salvinia species is that their leaves can either float on the water's surface or be submerged. This adaptability allows Salvinia, often known as water spangles, to thrive in a variety of aquatic environments. The floating leaves help the plant capture sunlight and carry out photosynthesis, which is essential for its growth. Meanwhile, submerged leaves can assist in stabilizing the plant within the water column.

In contrast, the other options do not accurately describe the nature of Salvinia. For instance, stating that all leaves are submerged would not represent the typical growth habit of Salvinia, as a significant portion of its leaves are indeed floating. Saying that Salvinia only produces spores overlooks its ability to propagate vegetatively through runners, which is a common characteristic of many aquatic plants, including some species of Salvinia. Finally, the incorrect notion that Salvinia does not propagate vegetatively disregards its well-known capability to reproduce asexually, resulting in rapid colonization when conditions are favorable.