Water lettuce, or Pistia stratiotes, is a species of aquatic flowering plant belonging to the family Araceae. It is native to the tropical and subtropical regions of the Americas, where it grows in slow-moving waters, such as swamps, ponds, canals, and rice paddies.
Its name comes from its floating leaves which resemble lettuce leaves, but its scientific name means stratiotes (soldier) because of its ancient use as a battlefield dressing to staunch blood loss during war times in Greece and Rome.
Pistia stratiotes are the plant responsible for forming floating islands that are frequently seen in ponds and lakes throughout North America and parts of Europe. The scientific name, Pistia stratiotes, comes from the Greek word pistis which means faith, and stratiotes meaning soldier, presumably in reference to the shape of its leaves.
Sometimes called water cabbage or mekong weed, Pistia stratiotes is an aquatic plant native to the tropical regions of Asia, Africa, Australia, South America, and North America. While it can be found in many freshwater sources such as ponds and lakes, water lettuce thrives best in slow-moving water areas with abundant sunlight exposure such as swamps, marshes, and even ditches.
What is water lettuce?
Water lettuce is a floating aquatic plant belonging to the Araceae family. This type of water weed forms dense mats on top of still or slow-moving bodies of water, and it can also be planted in tubs and containers as an ornamental plant or in ponds for fish food.
It features thick leaves that float on top of calm waters and provide shade, making it ideal for aquaponics systems that include fish, as well as aquatic habitats with little sunlight such as mangrove swamps. Other common names for water lettuce include Pistia stratiotes and Nile cabbage.
According to all aquatic plants, they are annuals or perennials growing from short rhizomes. Their root system consists of fibrous roots which help them attach themselves firmly to their substrate so they don’t move around much when there is a current present.
How to grow water lettuce
To reproduce vegetatively, water lettuce uses stolons, which can be propagated either by division or by soaking seeds in the sand and keeping them partially submerged. Growing water lettuce in a water garden or a container outside in the full sun to part shade is possible in USDA plant hardiness zones 10 in the southern state.
Because it spreads so prolifically, the propagation of water lettuce is simple and easy. The process is as follows:
- Take a sharp pair of scissors and cut the stolon that joins the mother and daughter plants. Offshoots of plants, commonly called daughter plants or runner plants, produce their own root systems.
- The runner plant should then be removed and relocated to a new location. Unchecked propagation will typically lead to these plants becoming invasive.
How to grow water lettuce from seed
It is unusual to start water lettuce from seed, but it is possible. Below are the steps to starting water lettuce from seed:
- Bury the seed lightly in the sand.
- Make sure the soil and seedlings are well watered.
- The soil and seed should be submerged in water.
- As the seed sprouts, the container will fill with seedlings. The seedlings are now ready to be transplanted into your aquatic environment.
How fast does water lettuce grow?
Although it has a reputation for being a fast grower, you may be surprised to learn that it’s actually quite slow-growing. Water lettuce only reaches about six inches in height each month and requires little attention. This means that if you want a lot of water lettuce growing in your tank, it will take time and patience!
In fact, some owners have reported waiting up to six months before they saw significant growth. Of course, once you get it established, water lettuce can last several years with little maintenance.
How to overwinter water lettuce
Despite its name, water lettuce cannot withstand cold temperatures. In order to overwinter a plant, it must be placed in a smaller container of water (such as a fishbowl) and kept in an area that is warmer than 50 degrees Fahrenheit. It may be necessary to expose the plants to the full sun and fertilize them regularly.
Water lettuce care
Water lettuce, also known as swamp cabbage, has many uses in home and garden ponds. Although it is considered an invasive species to some places in North America, it has been used for hundreds of years as a greens ingredient in Asian cuisine.
It also serves as a temporary cover for fish fry from predators as well as floating islands of foliage that house beneficial insects. If you want to grow water lettuce, they are relatively easy to take care of once they get established in your pond.
Pistia Stratiotes is an aquatic plant native to the warm waters of Africa and South America but is now often found in tropical aquariums. Its small white flowers often bloom at night and are pollinated by moths and flies looking to lay their eggs on its leaves, which float on the surface of the water when they mature.
The only problem with this plant is that it grows very slowly and can get very invasive if left unchecked. Fortunately, there are lots of useful things you can do with Water Lettuce besides keeping it in your aquarium!
In general, it is a sun-loving plant. However, it will still grow in full shade. If you are growing water lettuce from seed, start with well-lit spots such as a patio or sunny windowsill and see how your plant performs there before moving it to a shadier area of your garden.
If you have an especially shady garden area where other plants refuse to grow, try planting water lettuce there to see if it will do better than its more finicky companions.
Water lettuce fertilizer
Pistia stratiotes is an aquatic plant that can be used to help remove excess phosphates and nitrates from your water by using it as a natural filter. In order to grow water lettuce, you’ll need to maintain a high concentration of nutrients in your aquarium. It’s best to fertilize with soluble phosphate and nitrate rather than fish food because it will have less of an impact on your pH levels.
To keep nutrient levels at proper concentrations, use no more than 25% of your total tank volume weekly with each application. Keep a close eye on your water parameters to make sure there aren’t any spikes or sudden drops; if you notice anything out of whack, it might be time for some maintenance! You should add 20-50 grams per 50 liters depending on how quickly you want results and whether or not you want to accelerate growth rates.
This plant thrives in water temperatures of between 24-29 degrees Celsius, and so benefits from a good circulation pump. It is recommended that you check your temperature regularly to ensure that it remains within these parameters.
Water lettuce is well adapted to moist environments, tolerating complete inundation for weeks at a time. Many plants can tolerate complete submersion for as long as 30 minutes without ill effects. When subjected to longer periods of submergence, water lettuce will begin to lose its characteristic green color and may eventually die.
As an adaptation to prolonged submersion, water lettuce’s root system is highly absorptive and consists of a dense network of roots growing near or just below soil level.
The normal humidity range is between 85 and 95 percent. Humidity that is lower than 70 percent for an extended period of time will cause wilting, eventually leading to death.
Water lettuce must be maintained within a relative humidity of 80 percent or greater; therefore, its susceptibility to excessive heat (relative humidity of 30-40%) may have evolved as a protective mechanism against hyperthermia.
Water lettuce flower
Pistia stratiotes have flowers that are small, whitish, and waxy. They open at night and close during morning hours. Pistia stratiotes are hermaphrodite plants having both male and female organs. The flowers emit a very sweet scent at night to attract pollinators like insects and bats. Pistia stratiotes have papery white petals that are partially open during nights or in humid environments but close in extremely dry conditions or when sunlight is present.
Is water lettuce edible?
No, though it is non-toxic, but it contains little nutritional value. In addition, water lettuce leaves contain silicon, which can be harmful to your liver if you eat large amounts of them. As a result, eating too much of it may cause diarrhea and other digestion problems in humans. Fish seem to like eating water lilies though; they often graze on their broad leaves.
What eats water lettuce?
Water lettuce is a source of food for many different animals, including fish and wading birds. Some crustaceans, snails, and insects also feed on water lettuce.
Some examples of fish that love to eat this plant are bluegill, black crappie, and largemouth bass. Birds such as herons and egrets enjoy dining on these plants in ponds. Even raccoons, opossums, and skunks will snack on it! It can be eaten by human beings as well; its crunchy stem tastes like celery when cooked or preserved.
Water lettuce turning yellow
Water lettuce that is not planted in clean water will turn yellow. Yellowing leaves can be caused by many other factors so keep an eye on your water lettuce and keep your aquarium clean. If a plant has been established for some time, it may also need fertilizer to help revitalize growth.
It is important to remove dead or yellow leaves as they could rot, which may cause odor or fungus problems in your tank, especially if there are high amounts of humidity and warmth.
Water lettuce benefits
This floating aquatic plant has been described as a superfood and has already been used as a potential source of biomass. It has a large number of different applications ranging from animal feed to biofuel production. The plants are loaded with essential nutrients like iron, magnesium, potassium, zinc, and vitamins A, B1, B2, and C.
They also contain anti-inflammatory properties and are an effective anti-cancer treatment. Additionally, water lettuce contains carotenoids which have antioxidant properties. In addition to these unique benefits, water lettuce contains protein, calcium, and dietary fiber. Both raw and cooked water lice have shown benefits in improving digestion.
Water lettuce medicinal uses
Native Americans used water lettuce as a food source and in poultices for poison ivy rashes. Its use as a food crop is limited because it has a bitter taste. Some cultivated varieties have been developed that lack bitterness and maybe good additions to salads, soups, or stir-fries.
It is also high in vitamins A and C, manganese, calcium, and iron. Small amounts of saponins have been found in water lettuce as well; these chemicals are toxic to some insects but are likely safe for humans.
Though Pistia stratiotes are sometimes called water cabbage, it’s not closely related to true cabbages (Brassica spp.) or other members of the mustard family (Brassicaceae). This aquatic plant has long green strap-like leaves with wavy edges.
Water lettuce vs water hyacinth
Water lettuce (Pistia stratiotes) and water hyacinth (Eichhornia crassipes) are aquatic plants grown for their bright colors and adaptability. However, when these two wetland specimens grow together, they can cause a big headache. With similar leaf shapes and growth patterns, distinguishing one from another isn’t easy — especially if you don’t have time to stop at your local pond store or specialty plant nursery.
Here’s how to differentiate between them:
Eichhornia crassipes is more commonly known as water hyacinth; its long roots entangle other vegetation as it floats on top of bodies of fresh or saltwater. It also releases chemicals that attract mosquitos in addition to causing problems with boating, fishing, and shipping channels.
The leaves of Eichhornia crassipes are dark green while Pistia Stratiotes is similar but has a lighter shade of green leaves with white margins around them. During blooming season, Pistia Stratiotes flowers are usually yellowish-white/green/brown spikes just below water level, whereas Eichhornia crassipes produce white clusters.
While both species tend to establish quickly, growing up to several feet per day, each has its own preference when it comes to living conditions.