Java Fern or Microsorum pteropus [my-kroh-SOR-um, ter-oh-pus] is a perennial water plant (fern) and member of the Polypodiaceae family.
The plant hails from Thailand, Malaysia, and parts of China.
Microsorum Pteropus Care
Size & Growth
Java Fern has deep green leaves and grows to be about 13” inches high, but in the wild, it can grow to be nearly 3’ feet high.
Because of its height, it’s a good choice as a background plant for an aquarium.
Planting it too close to the front will obscure your view.
It’s height makes it a good choice as a pond plant because, in an outdoor setting, the leaves will grow above the level of the water for an interesting display.
Flowering & Fragrance
The plant is made up of leaves, rhizome, and root system but no flowers.
The roots are very thin and dark brown and are suited more to clinging than to take up nutrients.
The root system is made up of very fine, hair-like tendrils creating a sturdy tangle around the object upon which they choose to anchor.
At the base of the plant, you’ll find a rhizome which performs the task of absorbing nutrients.
When the roots have firmly attached the plant to an object, the rhizome will begin to grow and will eventually cover the object.
Rhizomes in a natural setting can spread to be 6” inches across.
The leaves are deep green and leathery and quite tough.
They also have an unpleasant taste.
These two qualities make them a good choice in an aquarium or pond setting populated with herbaceous fish such as koi and goldfish.
The Java is impervious to their predations.
Don’t be alarmed if you see black lines and/or brown or black bumps on your plants’ leaves.
The lines are the plants’ veins, and the bumps are the spores that will grow into baby plants.
If the leaves of your plants grow out of the water, the spores may grow on the undersides of the leaves.
When they develop in this manner, they get blown off by the wind to relocate in a distant setting.
Light & Temperature
Java Fern is a low light plant. It cannot tolerate very bright aquarium lights or excessive exposure to the sun.
Many aquarists have found this plant does quite well with little or no light.
This is a tropical plant thriving in temperatures ranging from 70° – 75° degrees Fahrenheit (21° – 24° C), but it can tolerate temperatures as low as 60° degrees Fahrenheit (15° C) and as high as 83° degrees Fahrenheit (28° C).
Watering & Feeding
This plant is a freshwater plant, but it can tolerate some salty water.
Be sure not to allow the salt level of your water to go above 1g.
This plant prefers pH levels between six and 7.5.
If you’re keeping your plants in a setting where the leaves will grow out of the water, you must maintain a very high level of humidity.
A setting similar to the misting set up you’ll find in the produce section of your supermarket is recommended to keep these plants happy.
If you want to keep your Microsorum partially submerged, remember the roots and the rhizome must stay in the water.
Only the leaves should protrude.
If a great deal of leaf surface grows out of the water, you may need to provide extra nutrition to help the plant thrive.
Feed your Microsorum with aquarium fertilizer following packaging directions.
Ue a tablet or liquid form safe for aquatic animals.
Good aquarium plant fertilizer should contain:
… as well as micronutrients such as:
Naturally, you want to be sure the fertilizer you choose is safe for all forms of aquatic life.
This is especially true if you are keeping your plants in an outdoor pond or water feature which may attract wildlife.
Remember both fish and aquarium plants need clean water.
Do a partial water change of about 25% in your aquarium, water feature, or pond at least twice a month.
This will help remove excess nutrients, fish waste, and dropped food.
Unlike many aquarium plants, Microsorum doesn’t require a great deal of CO2.
It does need plenty of oxygen in the water.
Be sure you have plenty of surface area on ponds and water features and add oxygenation if possible.
All aquariums should be oxygenated.
Soil & Transplanting
Java Fern not only doesn’t need soil, but it also doesn’t like soil.
If you plant these aquarium/pond plants in soil, sand, or other substrates, the rhizomes will rot, and the plants will die.
Because these plants are epiphytes, they like to attach themselves to roots, rocks, and aquarium or pond ornaments.
When you place your new Java Microsorum in your aquarium or pond or water feature, just allow it to float and let it find its place to anchor.
If you want to control its placement, tie it lightly to a piece of driftwood, a rock, or an ornament using cotton thread.
This type of thread will hold the plant in place and will dissolve after the roots have gotten a firm grip.
Grooming & Maintenance
You may need to prune your Microsorum Fern occasionally.
Doing so will help them to grow more attractively.
Pruning is simple, just trim off the largest leaves (especially if they have become battered or damaged).
Only remove one or two leaves at a time, and be sure to trim them right next to the rhizome.
This will encourage fresh, new attractive growth.
How To Propagate Microsorum Pteropus
Microsorum is a variable water plant that grows in a rather rampant fashion throughout Malaysia, Thailand, and China.
It grows in all sorts of waterways, including bogs and ditches.
It typically grows either partially or fully submerged.
Java Fern propagates in several ways.
Underwater, the plants will develop spores on the edges of the leaves, which will develop into little plantlets.
Left on their own, they will disengage and float away to find their new setting.
Hurry this along by removing a leaf and relocating it yourself.
Alternately, remove individual plantlets and place them as you wish.
Well-established Microsorum will develop a very wide rhizome (up to 6” inches).
Young plants or pups will grow from the rhizome.
Microsorum Pteropus Pest or Disease Problems
Too much light will cause your Java to experience a condition known as Java Fern melt.
When this happens, brown or clear blemishes will appear on the leaves, and the plant will eventually disintegrate and die.
Remember Microsorum is a low light plant and excessive sunlight will kill it.
If you’re using artificial lighting, 1.5 W per gallon of aquarium or pond water is desirable.
Even this small amount of light may be too much, and you may choose instead to backlight your aquarium rather than using overhead lighting.
In this case, low light LED lights are preferable.
If you determine excessive light is the cause of your problem, you must prune off damaged leaves and then turn off your aquarium lights and cover the tank with a towel or blanket for three days to give the plants a chance to recover.
In an outdoor setting, you must prune back damaged parts of your plants and then determine a way to provide more shade.
In upon setting, you may set up an umbrella or shade cloth and possibly move potted plants around the edges of the pond to shade it.
For water features, you may need to move the whole thing to a shady or setting.
Java Fern melting is caused by cyanobacteria or blue, green algae growing in your tank.
This is caused by a lack of nutrients in the water.
If you find this is the case, you must clean and peel away the film of cyanobacteria from your ferns and other aspects of your tank.
Do a partial water change of 25 to 50% and give your plants a dose of fertilizer.
Be sure to keep nutrition levels high so cyanobacteria will not return.
Remember a lack of fertilizer alone can cause Java Fern to melt.
It’s easy to see there are many reasons to keep your plants well-fed.
Too much salt in the water may also cause leaf melt.
Be careful not to use too much fertilizer as this can cause salt buildup, cloudy water, promote algae growth, and may even cause Java Fern melt.
Watch out for tiny snails that may hitchhike home on new water plants.
These little snails will take up residence in your Java Fern.
They won’t hurt your ferns, but they can quickly take over your aquarium.
Get yourself an assassin snail to eat up these little invaders as they appear.
Assassin snails make a nice addition to your tank and will happily clean up leftover fish food, fish waste, and algae.
Is The Java Fern Toxic or Poisonous?
Toxicity of this plant is unknown, but it is thought to have a bad taste, which protects it from being eaten by fish and aquatic creatures.
Since it is typically contained in an aquarium, pond or water feature, you needn’t worry much about its toxicity – just don’t eat it!
Is The Java Microsorum Plant Invasive?
In its wild setting, Microsorum grows in very large clumps and spreads with wild abandon over reefs, rocks, and driftwood.
It’s very adaptable and easy to grow in a wide variety of settings.
Predictably, this enthusiastic reproducer is considered potentially invasive in any climate supporting it.
Remember plants of all sorts are eventually able to evolve and adapt to the climates they find themselves in.
Never dispose of extra water plants or animals by releasing them into the wild.
If you live in a semi-tropical or tropical area that tends to flood and/or has high winds, it’s best not to use this plant in an outdoor setting.
Suggested Microsorum Pteropus Uses
There are several different varieties of Java Fern, to amass an interesting collection of these hardy underwater plants for your aquarium, water feature or pond.
Each variety has a slightly different appearance and leaf formation.
- Windelov Java Fern is also known as Lace Java Fern.
- It has a very lacy and delicate leaf shape.
- This plant is slightly smaller than the versions which have more lance-shaped leaves.
- Philippine Java Fern is a wide leafed variety.
- The surfaces of the leaves are interestingly textured.
- Trident is another delicate version that has feathery leaves, often described as sharp or needlelike.
- The fronds emerge from a central point upon the rhizome.
- Narrow Java Fern has a wide leaf base tapering into flowing teardrop-shaped leaves.
- This species combines the textured leaves of Philippine Java Fern and the needlelike leaves of Trident.
- Undulata has leaves narrower at the base and wider at the tip.
No matter which species you choose, the care of Java Fern is quite easy.
The plant grows enthusiastically as long as it is kept in soft lighting and within the desired temperature range.
As an aquarist, you naturally want to keep your fish happy and content, and adding several different varieties of this easy-care water plant can do just this.
As an outdoor gardener, adding an interesting water feature or pond showcasing these pretty plants can bring a great deal of interest to your garden.
Because these plants can grow quite large, remember you’ll need at least a 10-gallon aquarium for a single plant.
Because they reproduce quite freely, you also need to plan on setting up more aquariums, ponds or water features and/or making friends with other like-minded aquarists or gardeners with whom to share.