Primrose Creeper Ludwigia Peploides

The yellow flowers on Primrose Creeper persist most of the summer making this a favorite blooming plant.

Flowering time is June-September. The foliage is ovate and shiny and as the name implies it creeps across the water.

Some like to grow it in the waterfall and let it cascade down the rocks.

Grown this way it discourages algae that grows on the rocks. 

It is hardy zone 6 or higher

This plant can be potted, or the rooted ends tucked into the rocks of a streambed or water fall.