How to choose floating plants?

In ponds as in aquariums (and even in poubellariums), floating plants are an integral part of a balanced aquatic ecosystem.

Their particular position allows them to provide services that only they can offer.

Indeed, the surface of the water, the place of all exchanges, is the richest area in life and the most important of aquatic environments.

In the pond, the floating plants are the ones we see the most.

In a closed aquarium, these are the ones that are generally seen the least, except for their roots. To the point that one sometimes forgets that the surface is crucial.

 

The different species cultivated by Aquazolla (others are in preparation 💪) provide a complete range, meeting most needs and ecosystem services.

 

The common virtues of floating plants are as follows:

- shading or filtering of light (more or less pronounced).

- high purification capacity: the direct reception of light, not absorbed by water, makes their metabolism very efficient. They therefore have strong growth and eagerly consume nitrates, phosphates, etc. that pollute the water.

- they protect the fry by feeding them. Living just below the surface, the newly hatched fry can hide among their roots and find in this "superficial jungle" the infusoria they eat in abundance. Protection and feeding, therefore.

Here are their portraits, each species being more or less effective on each mission.

 

The water lens (Lemna minor)

It is the most well-known and the most common. Its growth is very strong, proportional to light, temperature, and the richness of the water in nitrates.
It therefore cleans up very significantly when these resources are available.
"She has the flaw of her qualities, since it is difficult to get rid of them. A simple fragment is enough to reconstitute an entire population. But why eliminate it completely? It is enough to limit its growth by collecting the excess: nitrates are transformed into lentils, and you thus easily eliminate them from the cycle."

An excess of lentils can deprive the water body of light.
It is therefore necessary to ensure that its expansion is limited.
But if you have goldfish or carp, know that they love it and will happily eliminate it themselves!

"Outdoors, winter limits it significantly, but does not eliminate it completely."

 

The great lens (Spirodela polyrhiza)

Less known and less widespread than the classic lentil, it has a slightly more reasonable growth! Its leaves are much larger and a bit reddish underneath. Its roots are a bit more abundant.

 

It is easier to contain than the common lens, since each individual is larger: thus, it is easier to remove the large lens by hand or with a net.

On the other hand, few fish eat it. It is probably too big for their mouth.

For the rest, she performs exactly the same functions as her cousin.

"It regresses strongly in winter, waiting for spring in a dormant form at the bottom of the water."

 

The Azolla (Azolla caroliniana)

A very singular plant, Azolla is, like lichen, a symbiosis associating two species: a floating fern and a cyanobacterium. It is this particularity that makes it capable of fixing nitrogen from the air, and thus able to grow even in water without nitrates.
"Her pollution-cleansing power is legendary, as she possesses a specific gene that allows her to bind heavy metals!"

She is often capricious.
"With her, it's heads or tails!"
"If it thrives, it develops very quickly, but otherwise it stagnates or disappears without any very obvious reason."
Its color, likewise, varies from dark red to green with all the intermediate shades, but it is she who decides...
Its "roots" (dark filaments) are quite long (1 to 3 cm) and provide an excellent refuge for fry.
The Azolla loses its roots during transport (and therefore shipping), but also often as soon as it is moved to a new pond or aquarium. This is normal, and it is its way of adapting to new conditions.

"Its appearance is superb in a basin, its unique texture producing a magnificent velvety green-red or inimitable pink surface."
In the aquarium, she seems not to appreciate lids that are too close.

In the basin, it often survives the winter, if necessary by dormant forms falling to the bottom.

 

The three-lobed duckweed (Lemna trisulca)

This close relative of the lentil also floats, but UNDER the water!

Unlike almost all floating plants, its fine leaves are therefore submerged. This detail changes everything, as its photosynthesis does not take place in the air but in the water, it is an oxygenating plant.

This also gives him another quality.
Its leaves AND its roots being aquatic, it forms a cushion of several centimeters in which the fry are completely out of reach of adult fish. They find maximum security there, while remaining close to the surface and the infusoria that abound around this floating plant.

Not very demanding in light, it is often associated with other plants that shade it a little, or in a less sunny area of a pond.

Its growth is slower and more limited than that of other lentils, and it survives the winter outdoors.

 

The Salvinia (Salvinia natans)

Another true floating plant, and what a plant! It forms fronds of several leaves (generally 6 to 10), which then fragment to multiply infinitely.

She dies in winter in the pond, killed by the frost.

"Its growth potential is very strong if it has warmth. It forms a very particular surface, full of nuances, as the leaves change color according to their age, ranging from light green and green-brown, on the same frond. But above all, the surface of the leaves, absolutely waterproof, and covered with tiny hairs gives it a texture that changes according to the light."

Its roots are short.

In an aquarium all year round, it is original because its fronds "navigate" if the surface is animated, and in this case provide changing soft light effects in the aquarium.

 

 

These few descriptions should help you in your choices.

But you can also let nature choose what is relevant for your little ecosystem, by installing a small amount of each species. You will then see which ones dominate and thrive, and which ones decline (sometimes to catch up later...).

In a pond, for example, some species will take their place in the shade, others will thrive at the edge in shallow water, or will proudly shade the open sea!

 

You will thus choose to be the screenwriter or the observer... or both!