Crinum thaianum

Crinum thaianum, also called the Thai onion plant or water onion, or Phlap Phueng Than, is an emergent plant species, endemic to the coastal plain of Ranong and Phang Nga Provinces, Thailand. Its natural habitat is to grow along the banks of flowing, medium- to fast-running streams, where its roots and bulb are submerged in the sediment, while its leaves grow long in the current and can access fresh air at the surface. When in bloom, the flower is an umbel of large, showy blossoms above the waterline. These growth habits make it a popular addition for tropical aquaria, and it is sold in many regions to be used specifically for growth within displays of tropical fish. It also serves the added benefit of oxygenating the water and absorbing ammonia, which is toxic to most aquatic animals. In nature, however, the species is threatened with extinction, and diminishing rapidly, due to habitat destruction....read more on Wikipedia.