Echinodorus, Amazon sword plants, belong to the frogspoon family. The native frog spoon Alisma plantago-aquatica grows, for example, at the edges of ponds. This gave the family of the frog spoon plants the name Alismataceae.

How Echinodorus reproduce

Reddish sword plant Photo: Ralf Fischer

With well-growing Echinodorus, an inflorescence can be formed sooner or later under species-specific conditions. The flowers of Echinodorus are quite inconspicuous. The petals are white.

First, long, long flower (stand) stalks or flower (stand) stalks form, on which small knots or thickenings form at more or less equal intervals. After some time, flowers form on these thickenings above water, and small plants under water, which are called adventitious plants.

Some Echinodorus also develop the plants in the air, but some only when they are immersed in water. If you want to be sure that these little plants will form, you should immerse the inflorescence in water. Then these little plants will definitely form. After a while, when they are big enough and have already rooted, they can be separated and planted by turning them slightly around the axis.

With some Echinodorus, eg Echinodorus horizontalis, flowers are also formed under water. At least in the case of Echinodorus horizontalis, seeds also form under water because the flower can pollinate itself.

Many Echinodorus can develop multiple types of peduncles. This is particularly evident in small species such as E. tenellus. Under certain conditions, these also form emersed, above water, only runners or shorter-stalked flowering stalks grow. The whole thing seems to depend heavily on temperature and light. Presumably dry season conditions, i.e. lots of sun or warmth and drought, stimulate the formation of flowers. Here the seeds also make sense for the plant.

Mixed forms of these types of flower stalks, which form both flowers and adventitious plants, are found in the larger Echinodorus sp. No rarity.
Plants with flowers usually have much shorter flower stalks than plants that only form adventitious plants.

Some Echinodorus form emersed leaves under long-day conditions, i.e. when they are illuminated for more than 12 hours, and others only form flowers then.

Echinodorus berteroi (cellophane plant) Photo: Ralf Fischer

In nature, Echinodorus are not usually constantly under water. In nature, the various Echinodorus species usually grow as swamp plants, i.e. not submersed (submerged) all year round, but mainly emersed (above water).
On land, the offshoot plants push the stalk down over time until their roots eventually find a foothold in the soil. In the aquarium, the adventitious plants do not grow large enough to be able to push down the usually strong stalk so far.

In the aquarium, the inflorescence stalk is best left in the water or pushed under water. The plants then grow quite well and soon put down roots.
In open aquariums, the humidity is usually too low, so that no flowers or adventitious plants form or they dry up quickly.
In closed aquariums, the shoots close to the light often get too hot. In both cases, the parts above the water often dry up. Only when the humidity above water is high enough will offshoots also develop above water.

As soon as the adventitious plants have developed some strong leaves and roots, they can be carefully twisted off the stem and planted.
The stalk itself can be left on the plant for now. By carefully twisting off the young plants, the stem remains undamaged, can develop further and new young plants emerge.

“Due to the design” there can be three little plants at each node. Usually only one or two plants are formed and the others are dormant. If the progrowth is now removed, the second or third plant often sprout.

It is also possible to cut off the adventitious plants and plant them with the remaining short stalks. Of course, cutting off or cutting through the stem prevents the stem from growing further and further flowers and young plants from forming.

If the young plants are difficult to anchor in the ground, they can be anchored with a U-shaped paper clip. When the plants have grown, the clip should of course be removed again. The small plants grow particularly well and quickly if they find nutritious substrate, for example sand enriched with clay as subsoil.

Even small plants without roots will usually form roots if they are simply thrown into the aquarium. In the aquarium, the plants can probably absorb all the necessary nutrients through the leaves. Roots are not usually formed in a glass of water and leaves are shed. Presumably, nutrients are missing in the water glass.

If adventitious plants are already growing emersed (above water), a window sill culture can be attempted. Otherwise, the changeover from keeping them under water to keeping them above water is often difficult.

On the other hand, adventitious plants that have developed above water can usually be easily converted to being kept under water.

Echinodorus Photo: Norbert Heidbüche

If the inflorescence stalk is cut off just after the root, the rest die down to the root and decompose. The cut stem part can float in the water. Then the little plants will appear. However, they will not become as vigorous as if they were left on the plant. The second or third plant at the node may not sprout either.

Propagating Echinodorus from seeds is very laborious, as this requires flowering, pollination and seed ripening. Echinodorus seeds look like tiny nutlets, almost comparable to caraway seeds, only slightly smaller.

With luck, one or the other seed will germinate. If not, they may be seeds from plants that need to be pre-treated first. For example, some seeds need to be rubbed with sand, others need a heat shock before they are ready to germinate.

When the seeds germinate, it can take many months before the plant is large enough to recognize the Echinodorus species. The leaves must first be about 10 centimeters long.

Commercial Echinodorus are predominantly propagated by stolons as it takes far too long to grow from seed into salable plants for commercial purposes. The only Echinodorus species that can only be propagated from seed is Echinodorus berteroi. That is why the plant is hardly offered in the trade. However, seed propagation is essential for crossing attempts, since chromosome exchange only takes place via generative propagation.

Why newly bought Echinodorus shed their leaves

Amazon sword plant Photo: Ralf Peters

Many aquatic plants, including the Amazon sword plants, are cultivated emersed, ie above water or in swamp culture. So they grow very fast and dense. If these plants are planted underwater in an aquarium, they will eventually shed the above water leaves and new underwater leaves will grow back.

The unsightly brown old leaves can be snapped off with your fingers or cut off with scissors.

It is unclear whether more nutrients are released back into the aquarium water when the leaves dissolve or whether the dying leaves remove more nutrients from the plant.

There is a suspicion that algae-inhibiting substances enter the aquarium when Echinodorus leaves decay. In at least some tanks, it was found that less algae grew when the dead leaves were left in the tank than when they were removed. However, these are not systematic studies.

Echinodorus can take up to 6 months to get used to it. Initially, the plants continue to feed on the nutrient reserves that they brought with them from the aquatic plant nursery for a while. Only after these reserves have been used up do the leaves begin to decompose.

Amazon sword plant Photo: Tanja Pirenz

However, the old leaves are not always thrown off radically when you get used to it. Sometimes the adjustment is completely unspectacular and the plant just keeps growing. The acclimatization process then only becomes visible when new leaves grow back in the form of the underwater leaves and no longer in the form of the above-water leaves.

During the adjustment, the aquarium is supplied with the normal dose of a good aquarium plant fertilizer to prevent iron chlorosis or other deficiency symptoms.

During the transition, the densely grown roots also die off. The dead plant parts then decompose and putrefactive gases are created in the soil. This can be avoided by planting the plants individually and at a distance.