Creeping primrose-willow

Description

Ludwigia repens is an aquarium plant native to southern United States, Central America, and the Caribbean, where it grows along the edges of various water bodies. It often forms dense, trailing populations in shallow water, with shoot tips growing above the surface. This species is highly variable and hybridizes easily with other Ludwigia species, making scientific identification challenging. Ludwigia repens is a widely available aquarium plant, with several forms sold in trade. A popular variety has round leaves and is marketed as "Ludwigia mesakana" or "mesacana". The plant's flower structure is distinctive, featuring four small yellow petals on the emersed form. Ludwigia repens grows well under low light conditions (0.4 watt per litre) without CO2 fertilization. When exposed to strong lights, it develops a horizontal habit with many lateral shoots. Its reddish coloration is enhanced by sufficient light (0.5 watts per litre or above), moderate NO3 levels (around 5 mg/l), high phosphate content (1.5-2 mg/l), and adequate iron and micronutrients. Propagation is simple, as stem plants typically require: cut off lateral or top shoots and replant them in the substrate, discarding the rest of the plant. Ludwigia repens can be used in aquascaping as a background, middle-ground, or foreground plant, provided it is regularly trimmed to maintain its desired shape.