Spirodela polyrhiza

Species description

Care, breeding and tankmates

Plant profile

Placement

Floating

This is a floating plant that rests on the water surface, forming a dense canopy. It should be kept in open areas where it won't completely shade out demanding light-loving plants below. Baffles or feeding rings can be used to control its spread.

Botanical form

Floating

It features relatively large, rounded to oval leaves (fronds) that are bright green on top and reddish-purple underneath. Unlike smaller duckweeds, it develops a prominent tuft of several roots dangling beneath each frond. The distinct reddish underside helps differentiate it from common Lemna species.

Growth

Fast

Growth is incredibly rapid under favorable conditions, quickly covering the entire water surface. Its reproductive rate accelerates with high light and abundant macro-nutrients. Frequent removal is often necessary to keep the population in check.

Substrate

None

As a floating plant, Spirodela polyrhiza does not require any substrate for its cultivation. It develops hanging roots that absorb all necessary nutrients directly from the water column. This makes it an excellent choice for bare-bottom tanks or setups where substrate conditions are not prioritized.

Column fertilization

Recommended

Water column fertilization is absolutely essential as this plant has no access to the substrate. Comprehensive liquid fertilizers rich in nitrogen, potassium, and trace elements will fuel its rapid growth. Iron deficiency may manifest as pale or yellowing new fronds.

Root fertilization

None

Root fertilization is not applicable because this is a strict floating plant. Its root tufts hang freely in the water to extract dissolved nutrients. Substrate nutrients are entirely inaccessible to this species.

Trimming

Regular

Trimming is not required; instead, population control is achieved by netting out excess handfuls of the plant. Regular culling is necessary to maintain gas exchange at the surface and allow light to reach submerged plants. Discard removed plants responsibly to avoid introducing them to local waterways.

Propagation

Division

Propagation occurs prolifically through vegetative budding, where new fronds continuously grow from the edges of mature ones. Under ideal conditions, the population can double in just a few days. Occasionally, it may also produce tiny, inconspicuous flowers, though vegetative reproduction is dominant.

Sensitivity

Moderate

It is somewhat sensitive to very strong surface agitation, preferring gentle to moderate flow. High humidity directly above the water surface can sometimes cause rotting if condensation drips heavily on the leaves. It is generally tolerant of a wide range of water parameters.

Layout role

Floating, accent

It plays a crucial role in providing shade for low-light plants or shy aquatic livestock. The hanging root structures offer excellent hiding places for fry and shrimp. It is frequently used in open-top tanks or breeding setups to maintain pristine water quality.