Alternanthera hassleriana (Hassler's Alternanthera)
Botanical name: Alternanthera hassleriana
Common names: Hassler's Alternanthera, Neptune's Crown
Family: Amaranthaceae
Origin: South America
A water plant that will float across the water surface. The internodes of Alternanthera aquatica are filled with air, as adaptation to its life as a floating plant, and look "bloated". Dainty white flowers.
Similar plants: Alternanthera hassleriana (Hassler's Alternanthera)
Link to this plant:
https://toptropicals.com/catalog/uid/alternanthera_hassleriana.htm