Rotala Rotundifolia, Sunset

• Hardiness: Easy
• Light Needs: Medium
• Plant Structure: Stem
• Family: Lythraceae
• Genus: Rotala
• Region: Asia
• Location: Southeast Asia
• Size: Individual stem width: 1.5-2cm (0.75-1in)
• Growth Rate: Fast
• Can Be Grown Emersed: Yes
  

Rotala rotundifolia is a classic aquarium plant. While its origins are in southeast Asia, where it grows as a weed in rice paddies and wet soils, it now can be found through many parts of the United States. In the U.S., it was introduced with rice seeds shipped to the southeastern United States. This plant can be differentiated from the closely related R. indica by the differences in the two species' inflorescences. R. rotundifolia bears groups of terminal inflorescences while R. indica has solitary flowers on the axis of the leaves or short axillary spikes. R. rotundifolia is one of the most commonly available aquarium plants available through online venders as well as many local fish stores, although it is still frequently sold in error as R. indica .

R. rotundifolia is an easy red plant to grow in the aquarium. While it will grow in medium light, this plant really needs high light to show its true colors. When lit well, the plant will grow at an angle over the substrate instead of straight up. To encourage red coloration, R. rotundifolia should be kept well lit (2.5 watts per gallon or more) with no shading. Lean nitrate levels (~5 ppm), high phosphate levels (~1.5-2 ppm), and heavy iron/micronutrients dosing will help produce intense colors out of this plant. By varying these conditions, one is able to bring out various shades from pink to yellow.

To propagate, simply snip off a healthy stem and replant into the substrate. Pruning off the top portions of this plant and leaving the rooted portions in the substrate promotes very bushy growth as the plant should produce a multitude of side shoots. Pruning can also be done by discarding the rooted portions and planting the top portions into the substrate. If allowed to grow on the surface, the plant will also produce many side shoots from each node along the stem.

In aquascaping, this versatile plant can be used in the midground and background positions as a focal point or reddish accent. It is commonly used in both Nature Aquarium style and Dutch style layouts.