Proserpinaca palustris, or mermaid weed, is distributed in the entire east and south-east of the USA, on some islands of the Caribbean as well as in Central and parts of South America in ditches, ponds, rivulets and swamplands. Throughout its wide area of distribution, this plant has developed many different varieties, depending on the region.
P. palustris is not really a new aquarium plant, it has been cultivated in the USA and Europe for decades. For example, it was presented in the publication "Wendt'sche Blaetter" in the 1950s. However, the mermaid weed only gained international attention when it was imported as new plant from Cuba by Tropica.
The Cuban variety of Proserpinaca palustris seems to differ from its conspecifics from North America. In European trade, there's probably only the Cuban form of the mermaid weed to be found.
This plant is quite easy in culture, however, it needs some time to develop from its emersed green to its submersed orange-red form. Medium to strong light (0.5 watts per litre or more) is necessary for healthy growth and beautiful colours. It is also recommendable to add CO2 to the water to bring this plant to its full potential. A low level of NO3 (5-10 mg/l) and a high level of PO4 (1.5-2 mg/l) is beneficial to robust, compact development and a deep orange-red colour. Higher nitrate values induce the plant to assume light orange to green hues. A constant iron supply should be safeguarded to prevent the colours from fading.
P. palustris is not a fast grower and does not form many lateral shoots. When cutting back, consider re-planting the upper part of the shoot instead of the old plant. However, for propagation, the old part can be left in the aquarium, though. New lateral shoots will form on it, which may be cut off and re-planted, too.
This red-orange-coloured plant is an excellent choice for smaller aquaria. It neither grow very high nor very fast and it is an optimal eyecatcher in the middleground or the foreground, where it draws looks with its colour and its finely structured leaves.
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