Which Plants Grow in Plain Water?

• Some plants need no soil and naturally grow floating in freshwater. Design Pics/Valueline/Getty Images

  Several species of plants grow without soil in aquatic habitats, dangling their fibrous roots in the water to gather nutrients. Warm water, abundant sunlight and gently moving or smooth water surfaces provide the best conditions for these floating plants to grow. If water contains an overabundance of nutrients, such as from fertilizer runoff from nearby farm fields or lawns, excessive grow occurs, resulting in so many plants that the water's surface becomes fully hidden from view.

Duckweed

• A frog peeks up through a cluster of tiny duckweed leaves. frog image by Alison Bowden from Fotolia.com

  Just over 10 species of duckweeds (Lemna spp.) grow in still water ponds across the globe. Each leaf is tiny and floats on the water surface, anchored by a long thread-like root that dangles downward. In warm weather, it buds and produces new plants, eventually creating a smooth but thin mat of leaves all across the water surface. Both fish and ducks eat the vegetation that rejuvenates each year to sometimes fully mask the water in a pond.

Water Lettuce

• A rosette of water lettuce. laitue d'eau image by Unclesam from Fotolia.com

  A rosette of light green, ribbed leaves that float on the water about 4 inches tall, describes the tropical floating plant named water lettuce (Pistia stratiotes) or shell flower. Killed by cold water or frost, water lettuce produces spreading and floating stolon stems that create new plants. Thus, this plant becomes a dense mat of leaves on the water surface, often regarded as a noxious weed in subtropical and tropical habitats where freshwater fishing or shipping occurs. Water lettuce is a pantropical species, meaning it is native to tropical freshwater bodies all around the equator.

Mosquito Fern

• Sometimes people call the mosquito fern (Azolla filiculoides) "fairy moss" because of the lacy flat fern-like leaves that spread across the water surface like hoarfrost. In full sun exposure, the green leaves attain a rusty red coloration. According to Peter Robinson, author of "The Practical Rock and Water Garden," this aquatic plant survives cold winters by producing tissue masses that sink to the lake bottom. Once spring's warmth returns, they float to the surface to develop leaves no more than 2 inches tall. Mosquito fern is native to mild winter areas of both North and South America.

Water Hyacinth

• A thicket of floating water hyacinth plants. aquatic plants image by JoLin from Fotolia.com

  Today the water hyacinth (Eichhorina crassipes) invades and clogs waterways across many parts of the world where winter frosts and cold do not kill plants. Native to northern South America, water hyacinth grows from swollen, buoyant stems and club-shaped leaves. A hairy mass of roots dangle into the water. In sunny locations, each plant yields a highly attractive spike of lavender-blue flowers -- the reason it's called the water hyacinth. In some U.S. states, it is illegal to grow or sell this noxious aquatic weed.

Jesuit's Nut

• Sometimes called water chestnut or water caltrops, Jesuit's nut (Trapa natans) is an annual plant that sprouts each spring from seed once no threat of frost occurs. Creeping, floating reddish stems remain just below the water's surface and yield diamond-shaped green leaves. White flowers occur in summer, followed by spiny black seeds with a four-sided shape. Jesuit's nut hails from slow-moving or still waterways across Europe, Asia and Africa, according to the "A-Z Encyclopedia of Garden Plants."

Frogbit

• Looking like a tiny waterlily, frogbit (Hydrocharis morsus-ranae) develops shiny green leaves that are rounded but kidney-shaped. These leaves float on the water's surface in a rosette cluster and plants produce white three-petaled flowers in summer that jet up 4 inches. Frogbit forms a mat in the water, interconnecting its runner-like stems just below the water's surface. The vegetation spreads indefinitely.

Water Soldier

• Native to Europe and northwestern Asia, water soldier (Stratiotes aloides) grows as a partially submerged floating plant, forming pineapple or aloe-like clusters across the pond's surface. In summer, the plant's thin leaves rise further up from the water to display tiny white flowers with a pink blush. According to Robinson, water soldier grows 16 inches tall, but spreads indefinitely in the water.