Plant atlas

Geographical Origin and Habitat: Lemna spp., commonly known as duckweed, has a cosmopolitan distribution and is found on nearly every continent except Antarctica. It inhabits calm, still, or slow-moving freshwaters, such as ponds, lakes, ditches, and nutrient-rich wetlands. In these habitats, it forms dense green mats on the water surface, adapting to climates ranging from cold temperate zones to hot tropical areas.

Taxonomy & Genetics: It belongs to the Araceae family (subfamily Lemnoideae) and consists of several highly similar species, including Lemna minor. Genetically and physiologically, it is considered one of the simplest and fastest-replicating vascular plants. It is widely studied in scientific laboratories due to its ability to double its biomass in less than 48 hours under optimal light and nutrient levels.

Physical Structure: The structure is stripped of non-essentials: it consists of a tiny, flattened leaf-like body (known as a frond) that floats on the water surface, lacking a true stem. A single filiform rootlet hangs down from each frond, which does not anchor into any soil but acts as a gravitational stabilizer and an organ for absorbing nutrients directly from the water.

Color & Texture: It exhibits a uniform, bright light-green color, which is highly vibrant under moderate to strong light. The texture is smooth, with ovate or elliptical fronds that are slightly spongy and filled with air pockets to aid buoyancy. The upper surface is water-repellent, ensuring the plant remains floating even under minor surface disruptions.

Lighting & CO2: Duckweed requires moderate to high lighting to sustain its rapid growth. It does not require artificial CO2 injection because it sits at the air-

Water Chemistry: interface and absorbs carbon dioxide directly from the atmosphere, making it highly efficient and independent of dissolved inorganic carbon in the water.

Nutrition & Substrate: It requires no fertile substrate. It absorbs nutrients (specifically nitrates, phosphates, and ammonium) directly from the water column through its hanging root and the underside of its fronds. It is highly valued for nutrient export, acting as an efficient biological filter against excess nitrates.

Water Chemistry: Extremely adaptable, it tolerates pH levels from 5.0 to 9.0 and a wide range of water hardness. The ideal temperature range is 4 to 30 °C, and it can survive mild winter frosts. It does not tolerate strong surface agitation or direct spray from filters, which can submerge and damage the delicate fronds.

Space Management & Placement: As a strictly floating surface plant, its spacing must be managed carefully. Due to its rapid reproduction, it can cover the entire surface of a tank within days, blocking light from reaching lower plants and reducing oxygen exchange. Regular removal with a net is required to keep its population in check.

Pruning: No pruning is required. Management consists of physically scooping out excess biomass using an aquarium net. Discard of the removed duckweed responsibly; do not flush it down drains, as it can easily enter local waterways and become a highly invasive weed.

Risks & Diseases: Virtually disease-free, the primary risk is iron deficiency, which shows as rapid yellowing (chlorosis) of the tiny fronds. They will turn pale white or translucent and disintegrate. Another risk is complete nutrient depletion, which halts growth and causes the population to die off.