Last fall I got this small plant with floating leaves and small yellow flowers. It spreads asexually with stolons near the water surface. It also was winter hardy Zone 8-10 as it overwintered in the pond. This one was supplied to a plant store by a local company here in Victoria, Applied Aquatics.
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids
Order: Asterales
Family: Menyanthaceae
Genus: Nymphoides
Species: geminata