What distinctive feature do the flowers of Waterhyssop have?

Waterhyssop (Bacopa monnieri) is known for its distinctive growth habit, which includes forming floating masses of leaves on the water's surface. This characteristic enables it to thrive in aquatic environments, providing coverage and habitat for various aquatic organisms. The presence of these floating leaves is a key trait that helps distinguish Waterhyssop from other aquatic plants.

In contrast, while other options may describe qualities found in various plants, they do not accurately characterize Waterhyssop. For example, the flower petals' color and shape, as well as fragrance, are not defining traits of Waterhyssop. Instead, its ability to create floating masses of leaves is a significant aspect of its biology, making this feature the correct choice when identifying Waterhyssop.