Bacopa monnieri, or water hyssop, is distributed in many subtropic and tropical regions of the earth, growing on the shores of lakes, riversides and pond edges. It is even found in slightly saline locations near the seashore.
Depending on the water height respectively the season (dry or rainy), wild B. monnieri grows emersed, with a creeping habit and submersed with upright stems. Its emersed form develops beautiful light pink flowers in the leaf axils.
Bacopa monnieri is an Ayurvedic medicinal plant, known under the name of "brahmi" - a name for many medinical herbs, though. In Vietnamese cuisine, it is used as a vegetable.
Bacopa monnieri has been long known in aquaristics and is one of the most uncomplicated and widespread plants. Due to a mix-up, it has been erroneously sold as a novelty plant under the name of Hedyotis salzmannii. However, the real Hedyotis salzmannii (please refer to its plant profile) has quite a different leaf and flower form.
Typical for Bacopa monnieri are its thick, fleshy, light-green oblanceaolate leaves, i.e. they are widest near the leaf tip. The leaf tip itself is rounded.
This species is quite variable, and there are several forms in cultivation. One of them has a distinctly serrated edge, the leaves of another one have a round form.
Bacopa monnieri has little requirements regarding its growing conditions, however, it needs sufficient light. Optimal are 0.5 watts per litre or more. If the light is too low, the lower part of the plant tends to rot. Fertilising with CO2 is beneficial, but not a must. Besides stunted growth, B. monnieri does not tend to show dramatic nutrient deficiency symptoms. In aquaria with a high concentration of CO2 and a high light intensity the keeper should make sure that sufficient nitrate (around 5 mg per litre) and phosphate (around 0.25 to 0.5 mg/l) as well as a regular iron and micronutrient supply to guarantee faster and more robust growth.
This species is also said to be cultivable in brackish water of low salinity, experiences regarding the cultivation of Bacopa monnieri in brackish water might be interesting.
It is also easy to cultivate emersed. The substrate (e.g. normal potting soil) does not even have to be wet, just moist. During the warm months, B. monnieri can be kept outside, e.g. on the edge of a pond or in mobile water gardens, where the flowering shoots hanging down from the edges may have an especially attractive effect.
This robust stem plant maintains a vertical habit even under strong light when cultivated submersed. When it reaches the water surface, its emersed growth is still upright. Bacopa monnieri produces "pseudo runners" on the basis, which you can simply leave there or cut off and replant. For propagation, you can also cut off lateral shoots, which you replant.
With its light green colour and its special leaf form, Bacopa monnieri is a great accent plant for the back- and the middleground of aquaria.
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