Floating Pond Plants
Floating Pond Plants are of two types: those which are rooted with floating leaves and those which are not rooted in the sediment, but just float on the surface. Floating leaves are generally tough because they have to withstand the weather and water movement.
These act like ground cover on the water’s surface, providing fish the benefits of shade, protection and breeding areas. Ideally about 60 percent of the water’s surface should be covered, keeping water temperatures stable from morning to night.
Like submerged plants, floaters play an important role in creating a healthy natural balance for your water garden. The leaves of these plants float on the surface and shade the water, making it less hospitable for algae, cooling the water for fish, and giving fish a place to hide and to lay their eggs while spawning. You may decide not to include floating plants in your water garden, especially if it has a fountain. A fountain or waterfall that churns the water of a small pond will create too much commotion for them.
Most floating plants prefer full sun but will tolerate at least partial shade. Water lilies, as a rule, require at least six hours of sun a day to bloom. Lotuses are less particular about the amount of sun they receive than they are about temperature. They will bloom in partial shade, as long as they have a sufficient stretch of warm weather. Other options for flowers in partial shade include water hawthorne and pond lilies.
Aponogeton distachyus Water Hawthorne, Cape Pondweed
Description: Tropical gardeners can try this South African perennial with 8-inch elongated oval leaves. Heavily scented flowers, which bloom in both spring and fall, are held on a double spike; their purple-brown anthers look like freckles on the rows of white petals. Give water hawthorn a container 1 foot across and start it about 4 inches below the surface of the water, lowering it 1 to 3 feet.
Grows similar to a waterlily, but is smaller, with long, narrow floating leaves. Abundant blooms very early in the spring, and flowers smell like vanilla.
Tends to go dormant in hot summer weather, but excellent for spring and fall, before and after waterlilies are at their peak. In mild climates they usually bloom year round; in hot climates, they bloom in fall, winter and spring.
Mosquito Fern, Azolla Caroliniana
Description: Azolla is a tiny floating plant and is considered the smallest of the fern family. It is sometimes confused with Duckweed but actually looks very different. Duckweed has smooth bright green leaves and Azolla has crinkly rough textured leaves that are a darker sage-green in color and that develops a reddish tinge in bright sun. The two lobed leaves overlap in rows like fish scales. Threadlike roots hang down from the undersides of the leaves.
The dainty green snowflakes turn burgundy in autumn or in strong sunlight. This plant can easily become invasive. It can be useful if you need quick cover for a new pond and are willing to thin regularly.
Azolla likes sun but will tolerate some shade. It likes moist, warm air and does not do well in an aquarium. It usually will not survive the winter if temperatures fall below 50° F. It grows very fast and can become a problem in a big pond unless you can net it out regularly. If you want to cover the surface of a smaller pond fast, it is a good choice. This will give protection for small fish from birds. Azolla is used in Panama and elsewhere to carpet water surfaces to prevent mosquitoes from laying eggs. Fish like to eat Azolla when the diet is not balanced.
Eichhornia crassipes Water Hyacinth
Description: Water Hyacinths need full sun. It is a free-floating perennial plant that can grow to a height of 3 feet. The dark green leave blades are circular to elliptical in shape attached to a spongy, inflated petiole. Underneath the water is a thick, heavily branched, dark fibrous root system. The water hyacinth has striking light blue to violet flowers located on a terminal spike.
This is one of the most beautiful yet one of the most noxious water garden plants. One of the worst pest plants in California, Florida, Georgia, and Louisiana, it can't be shipped across state lines anywhere.
The free-floating plants are topped by 6-inch spikes of exotic looking lilac flowers. It helps keep pond water clear.
They can be wintered over indoors but they are fussy. They need lots of light, and moist air. Propagation is by runners at the water surface and is rapid. These are among the fastest growing plants in the world. In tropical areas they have clogged waterways and stopped navigation on rivers.
The hanging roots of the Water Hyacinths are great spawning material for Koi.
Be prepared: this rampant beauty can take over your water garden if you do not thin it regularly.
Warning: Water hyacinth is a very aggressive invader and can form thick mats. If these mats cover the entire surface of the pond they can cause oxygen depletions and fish kills.
Pistia stratiotes Water Lettuce
Description: Water Lettuce is shaped like romaine lettuce, the 8 inch leaves are undulating, velvety fans that stick up from the water, near white on base and undersides. Little green flowers are negligible, but the roots-which mature from white to purple to black-hang 18 inches and make a great fish nursery.
It is a noxious weed in southern states (it can't be shipped to California, Texas, Louisiana, or South Carolina); grow it as an annual north of Zone 8.
Floating Water Lettuce removes excess nutrients in the water and provides protection for the fish below.
Marsilea species Water Clover
Description: These appealing plants are technically ferns, but as their common name hints, they look like four leaf clovers or shamrocks. The most colorful is M. mutica, from Australia; its quartet of 3-inch leaves has two shades of green separated by a dark band. Water clovers can be grown in up to 12 inches of water, in which case their leaves will float. They can also be grown as marginal plants.
Description: True free-floating bladderworts are annual plants that lack roots but have flowers on erect stems above the water. The entire floating plant is only about 8 inches tall. Flowers emerge above the surface and are yellowish with 3-lobes and a spur underneath.
Underwater the leaf branches or petioles are fleshy and inflated with air which allows them to float. Leaves are whorled with 4 to 10 lateral leaves which fork often giving them a very delicate capillary appearance. Bladderworts are unique in that the underwater leaves bear small oval “bladders” that trap and digest small aquatic creatures.
Bladderworts are usually found in quiet shallow, acidic waters and can form dense mats.
Bladderwort is any aquatic plant of the genus Utricularia, some of whose leaves are modified as small bladders to trap minute aquatic animals: family Lentibulariaceae.
Lemna minor Common Duckweed
Description: Common Duckweed is a floating perennial and is commonly mistaken for pond scum in natural ponds. If you look closely, you will see a thick carpet of tiny, individual bright green plants which are actually very attractive. It has 1 to 3 leaves, or fronds, of 1/16 to 1/8 inch in length. A single root (or root-hair) protrudes from each frond. Duckweeds tend to grow in dense colonies in quiet water, undisturbed by wave action. Often more than one species of duckweed will be associated together in these colonies.
This free-floater is the water gardener's crabgrass; your pond is likely to have some sooner or later, probably introduced on the leaves or stem of another pond plant. This species occurs over most of the world. Each one of its light green oval leaves has a root hanging beneath it, put plants will cluster in large communities. Duckweed has its virtue, though, since it makes a nutritious food for goldfish and Koi.
To grow Duckweed in an aquarium, you need first to keep a sufficient amount out of the reach of your fish so it can reproduce. It prefers still or very slow moving regular aquarium water, florescent grow lights, and, if possible, a sealed environment to trap humid air. It will grow year around in this environment and you will be able to take out big clumps to feed your fish. Outside it will bleach out in full, direct sun so partial shade is ideal.
Does best in zones 3 to 11.
Hydrocharis morsus-ranae Frogbit
This free-floating species from Eurasia has shiny, 1 inch diameter leaves shaped like a water lily's and handsomely veined. Delicate cup shaped white flowers have three yellow petals near the base. New plants form on runners; in fall, turions (winter buds) drop to the pond bottom to overwinter. The green heart shaped leaves resemble a miniature water lily. This plant spreads easily.
Young floating leaves are often heart-shaped and have a spongy, purplish underside. Flowers are small, white (with 3 petals and 3 sepals) on a stalk about 1/3 the height of the leaves. Flowers can be above or below the waters surface.
Frogbit is a good choice for gardeners who don't have the time to do a lot of thinning.
Menyanthes trifoliata Bogbean
In spring, bogbean produces a foot tall spike of 10 to 20 white fringed, star shaped flowers that unfold from a pink bud and remain pink on the outside. Full sun produces more flowers. It has three-part leaves and can form a clump 3 feet or more in diameter. Bogbean will grow in a container 6 to 9 inches below the surface as well as in mud at the water's edge, where it will camouflage pond edges by creeping into the water with its spongy rhizomes. It likes the acidic environment of a true bog; it will grow better if you mix peat moss in the soil or container to increase acidity. It may not flower in the warmer parts of its range.
Nuphar species Pond Lily Spatterdock
These plants make a good substitute for water lilies where water is shaded, gently moving, or acidic. Globe shaped flowers are followed by oval berries. Plants develop long thick roots, divide them in spring. N. lutea bears 2 inch flowers. Its translucent submerged leaves can be a foot long, while the 16 inch floating leaves are leathery and slightly more pointed.
The best choice for an average size water feature if N. pumila, which can be grown in water only a foot deep. Zones 4-8. Japanese pond lily (N. japonica) has arrow shaped leaves and flowers blushed with red; a variegated cultivar, "Variegata", is suitable for small ponds and another, "Rubrotincta", has reddish orange flowers.
Nymphoides Floating Heart
These plants are often compared to water lilies. Unlike water lilies, all thrive in relatively shallow water-plant them 3 to 12 inches deep in a container 18 inches across. The 3/4" white or yellow flowers are usually fringed. Two native species are N. aquatica (banana plant), which bears 1/2" white flowers and forms tubers that look like tiny bananas, and N. cordata, which varies only in its tubers; both are hard to find. Zones 6-9.
Water snowflake (Nymphoides spp.)
Water snowflake (Nymphoides spp.) is part of a large family of what are commonly called water lily-like plants because their leaves float at the surface of the water while the roots are anchored in soil below, much like the habit of a water lily.
The plant is constantly reproducing, spreading runners out along the surface of the pond. Like water lettuce, you can pinch off the new plantlets to share with friends and help control growth. Because it's a hard grower, the Water Snowflake is great for ponds that suffer from constant algae blooms. The leaves will quickly spread across the water, providing shade and minimizing algae growth.
Popular Snowflakes for the water garden include:
White Water Snowflake, Nymphoides indica
White Water Snowflake has round, floating, 2 inch leaves that are green with maroon variegation. Because they exchange oxygen on the surface, they need to remain dry and away from the spray of waterfalls and fountainheads. Hardy in Zones 8-11.
Yellow Water Snowflake has very frilly, star-shaped yellow flowers, green leaves, and is hardy in Zones 5-11. This free-flowering plant has a fast-growing, running spreading habit. Ideally it grows in 4 to 24 inches of water.
Native to Australia, this plant has orange, star-shaped flowers and bright green leaves with dark red or brown variegation, and is hard in Zones 7-11.
Note: Some states include Water Snowflake on its list of invasive species. Check with your local government for its invasive species list.
Resources: Jennifer Zuri President of the International Waterlily and Water Gardening Society.
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When water plants have plenty of room and enough nutrients they will thrive and look wonderful.
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