Water hyacinth is a Floating plant.

Explanation:
Water hyacinth is a free-floating perennial aquatic plant that belongs to the family Pontederiaceae. It is a native plant of South America but has spread to other parts of the world due to its ornamental value and ability to quickly cover water surfaces. The plant has thick, glossy, and round-shaped leaves that float on the water surface, and its roots dangle freely in the water. The plant produces beautiful lavender-blue flowers that bloom above the water surface.

Floating plants are those plants that grow freely on the water surface with their roots hanging in the water. These plants do not have any attachment to the soil or substrate, and their roots are not fixed to the bottom of the water body. Water hyacinth is one such plant that floats on the water surface, and its roots absorb nutrients and oxygen directly from the water. The plant is known for its ability to form dense mats on the water surface, which can block sunlight and reduce the oxygen levels in the water, leading to the death of aquatic life.

In conclusion, water hyacinth is a floating plant that grows freely on the water surface without any attachment to the soil or substrate. Its leaves, flowers, and roots float on the water surface, and it is known for its ability to form dense mats that can cause environmental problems.