Marsh mermaidweed

Proserpinaca palustris, known as mermaid weed, is a stem plant distributed across the eastern and south-eastern United States, the Caribbean, and parts of Central and South America. The form most commonly found in the aquarium trade is a Cuban variant imported by Tropica, and the 'Mini' variety is a more compact selection suited to smaller aquaria. Under submerged conditions the plant gradually transitions from green to a striking orange-red, provided it receives medium to strong light of at least 0.5 watts per litre. CO2 supplementation is recommended to bring out the deepest colours, though the plant can persist without it in a well-lit tank. Growth is moderate, and the finely serrated leaves create an attractive accent in the midground or background. Nitrate should be kept low, around 5 to 10 mg per litre, with phosphate maintained between 1.5 and 2 mg per litre to promote compact growth and rich pigmentation. A constant supply of iron prevents the colours from fading. Propagation is straightforward: cut the upper portion of a stem and re-plant it; the remaining base will produce new lateral shoots. This plant is not a fast grower and does not form many side shoots, so it is best used sparingly as a focal point rather than a mass planting.