Eichhornia crassipes 
Annual, Aquatic, Perennial

USDA Zones: hardy in Zones 9 - 11; otherwise grow as an annual
Light: Sun
Height:  8 inches
Flower Colors: lovely violet-blue flowers with yellow blotches

Special Features:
Attractive Foliage
Easy to Grow

Grow this floating plant as an annual in all zones but 9 to 11. It spreads readily, with glossy rounded leaves held slightly above the water surface. In midsummer, it produces lovely blue flowers with yellow blotches. Its roots make good spawning grounds for fish, it helps filter the water, and it adds much-needed shade to water gardens. However, in warmer regions this plant is highly invasive and its sale may be banned. Even in colder regions, never dispose of plants in sewers or streams and don't transport over state lines.

Care
No special care needed, other than to make sure it's never out of water for more than a few minutes. If desired, in areas that receive frost, you could overwinter it in plastic containers under a grow light indoors.

Planting
Simply drop the plant into the water, root side down.