How to choose your floating plants?

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

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

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

 

In ponds, floating plants are the most visible.

In closed aquariums, these are generally the least seen, 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 💪) allow for a complete range, meeting most ecosystem needs and services.

 

The common virtues of floating plants are as follows:

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

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

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

 

Here are their profiles, each species being more or less effective for each task.

 

The water lentil (Lemna minor)

It is the best known and most common. Its growth is very strong, proportional to light, temperature, and the richness of the water in nitrates.
It therefore purifies very strongly when these resources are available.
It has the flaw of its qualities, since it is difficult to get rid of. A single fragment is enough to rebuild an entire population. But why remove it completely? Just limit its growth by collecting the excess: nitrates are transformed into duckweed, and you thus easily remove them from the cycle.

 

An excess of duckweed can deprive the bottom of the water of light.
So you need to make sure to limit its expansion.
But if you have goldfish or carp, know that they love it and therefore happily eliminate it themselves!

Outdoors, winter strongly limits it, but does not eliminate it completely.

 

The great duckweed (Spirodela polyrhiza)

Less known and less widespread than the classic three-lobed duckweed, it has a somewhat 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 common duckweed, since each individual is bigger: thus the large duckweed can be more easily removed by hand or with a net.

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

For the rest, it fulfills exactly the same functions as its cousin.

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

 

Azolla (Azolla caroliniana)

A very peculiar 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 growing even in water without nitrates.
Its depollution power is legendary, since it has a specific gene that allows it to fix heavy metals!

 

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

 

Its appearance is superb in ponds, its unique texture producing a magnificent velvety green-red or pink surface that is inimitable.
In aquariums, it seems not to appreciate covers that are too close.

In ponds, 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 three-lobed duckweed also floats, but UNDER the water!

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

 

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

Not demanding in light, it is often associated with other aquatic 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 duckweeds, and it survives winter outdoors.

 

The Salvinia (Salvinia natans)

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

 

It dies in winter in a pond, killed by frost.

Its growth potential is very strong if it has warmth. It forms a very particular surface, full of nuances, because the leaves each change color according to their age, ranging from tender green to green-brown, on the same frond. But above all, the surface of the leaves, absolutely waterproof, and covered with small 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 moving, and in this case provide changing plays of soft light 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 place in the shade, others will develop at the edge in shallow water, or will proudly shade the open water!

 

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

 

To learn more, also discover The magical power of plants, Why your friend’s plants recover better, the Sagittaria subulata naine for a natural ground cover effect, or also the Rotala advantage of natural aquariums to enrich your aquatic compositions.