Which of the following aquatic plants can reintroduce themselves easily and become problematic?

Hydrilla is known for its ability to rapidly reproduce and spread in aquatic environments. This plant can grow in a variety of conditions, making it highly adaptable, and it can propagate through both seeds and vegetative fragments. When fragments break away and establish new plants, this leads to dense growth that can interfere with native species, disrupt ecosystems, and hinder recreational activities like boating and fishing.

In contrast, native lilies, bamboo, and willow trees do not exhibit the same level of invasive behavior in aquatic environments. Native lilies are generally stable and contribute positively to their ecosystems. Bamboo, while it can become invasive on land, does not proliferate easily in water. Willow trees, though they can thrive in wetland conditions, do not have the same rapid reproduction mechanisms in aquatic settings as hydrilla does. Therefore, hydrilla stands out as the most problematic plant due to its aggressive growth and invasive nature in aquatic habitats.