The Japanese company Rayon Vert was the first to introduce Rotala sp. 'Vietnam' to the hobby. This Rotala hasn't been identified yet, but it is known that it populates shallow waters and wet ground in its native habitat. The submersed form is said to look very much like Rotala hippuris, however, it still has to be cleared up whether it indeed belongs to that species.
The requirements Rotala sp. 'Vietnam' are quite similar to those of Rotala wallichii. Moderate light leads to an overall green plant with red stems, whereas intensive light leads to a pretty golden colour. It also needs CO2 injection in order to grow well. The phosphate content of the water should be around 1 to 2 mg/l in order to obtain thicker stems, smaller internodes and a reddish tint. Iron and micronutrients should also be present in ample amounts. An iron deficiency results in small, weakly-coloured stems; an extreme lack may even cause the vegetation point to die off.
The growth habit of this form can be compared to that of Rotala wallichii. Rotala sp. 'Vietnam' grows vertically and produced many lateral shoots, especially if long shoots are allowed to grow along the water surface. Propagate like other stem plants: Make cuttings of top or lateral shoots and re-plant in the substrate.
Rotala sp. 'Vietnam' can be used in the middle- and background of a great number of layout types and is especially suited for aquascapes dominated by stem plants. It contrasts beautifully against red as well as green plants.
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[widget=aquaticplants/rotala-sp-vietnam]Rotala sp. 'Vietnam'[/widget]