The why, where and when of aquatic plants _lowres

Advocate file photo -- Water lilies thrive in backyard ponds and fountains.

The vision of water lilies, floating serenely, so mesmerized Impressionist painter Claude Monet he spent years painting them and nothing else.

Aquatic plants such as water lilies also fill important niches in the ecosystem of the water garden. Here’s a quick look at the types of plants to consider when envisioning a water garden and a brief explanation of why each plays an important role:

Deepwater plants:

These appear to float on top of the water but actually grow in pots submerged on the bottom on the pond. Long stems support the surface foliage and the blooms. Foliage from the deepwater plants provides shade, which cools the water and retards the growth of algae.

Deepwater plants to consider: Water lilies (especially miniature varieties if the pond is small), lotuses, water hawthorn, floating heart.

Submerged or oxygenating plants:

Like the deep-water plants, these grow in pots that rest on the bottom of the pond. But their stems and foliage are not tall enough to peek above the surface of the water. Growing entirely underwater, they provide food and hiding places for fish and pump oxygen into the water as they photosynthesize, helping to control algae. They also help remove excess dissolved nutrients from the water. Many oxygenating plants are used in aquariums.

Submerged plants to consider: Ribbon grass, hornwort, curled pond weed, willow moss, mare’s tail.

Marginal or bog plants:

These tall plants grow near the edges of the pond, also in pots, in water barely deep enough to cover the pot. Although they help filter the water, their main benefit is aesthetic: They provide height and proportional contrast to the overall composition. They require an underwater “shelf” for their pots to rest upon, but a few stacked bricks can do the trick if no shelf is present. Bog plants to consider: Taro, rush (including zebra, corkscrew and horsetail), aquatic cannas, dwarf cattails, native irises, shield pennywort, papyrus, arum lilies.

Floating plants:

These buoyant plants float at the water’s surface and require no soil. Their roots hang below them in the water and provide hiding places for small fish. Like water lily pads, the foliage of floating plants helps shield the pond from the sun, cooling the water and reducing the growth of sun-loving algae.

Floating plants to consider: Frog bit, water lettuce, fairy moss, mosquito ferns and bladderwort. Although water hyacinth, duckweed and giant salvinia are recommended in some climates, they are not desirable here because of their highly invasive behavior.