What is a common characteristic of rooted floating plants?

Rooted floating plants are distinguished by having rhizomes that anchor them in the sediment of their aquatic environment. Rhizomes are specialized underground stems that allow the plant to securely attach itself to the substrate while still allowing parts of the plant, such as leaves and flowers, to float on the water's surface. This characteristic enables the plants to access sunlight and carbon dioxide efficiently while remaining stable in the aquatic habitat.

The other options do not accurately describe rooted floating plants. For instance, plants that are free-floating with no attachment to the substrate lack the stabilization provided by rhizomes and can be easily moved by currents. Similarly, while long stems that float above the surface may describe some types of aquatic plants, they do not signify rooting or anchoring in the substrate. Lastly, not all rooted floating plants flower below the surface; many can produce flowers that are above water. This is a key distinction that differentiates rooted floating plants from other aquatic plants.