I've been growing Giant Leaf Bamboo on the side of my duck pond for over a year now and the benefits of growing bamboo by a pond include adding a lot of shade and stability to the pond edge. The Giant Leaf Bamboo sits in the semi-wetland area above the pond's marginal area where the Sweet Flag plant is growing. 

As both plants fill in, locking the soil in place and adding stability to the pond's water level and keeping the soil from eroding, the shade given by the Giant Leaf Bamboo keeps the soil from being dried out by the hot sun in the summers and the sweet flag creeps in between the culms of the bamboo to fill in the gaps. 

As the Variegated Sweet Flag continues to grow in, it is possible to give it more sunlight by trimming your bamboo culms back, thereby continuing to grow this beautiful companion planting pair by your duck or fish pond.

This is a Japanese Maple tree that is not particularly drought tolerant and will start to wilt if not given enough water, mkaing it an excellent choice for a pond-side planting. The Variegated Sweet Flag provides a beautiful ground cover for the Japanese Maple, keeping the soil around it more moist and more loose with its giant rhizome, allowing a beautiful meadowing effect to take place beside your pond. 

The Variegated Sweet Flag provides a sharp contrast to the dark pseudostem of the Black Thai Banana Plant when used as a companion plant pairing. There is also the benefit of the Sweet Flag's thick rhizome and evergreen leaves providing cover for the roots of the Black Thai Banana plant which is not particularly cold hardy past zone 9.