Sunset Rotala

Rotala ramosior 'Sunset' is the red trade form of Rotala ramosior, a stem plant from North American wetlands, where it grows in lakes, streams and irrigation ditches. The wild species produces green submersed leaves; the form sold in aquaria turns red under light, and is also traded as Rotala sp. 'Sunset' or Ammannia sp. 'Sulawesi'. Flowgrow treats the red form as a likely variant of R. ramosior and files it under the species name, family Lythraceae. It is a demanding plant. The page lists it as difficult, with slow growth and a strong light requirement; the optimum temperature is 22 to 28 °C, and it prefers soft, acidic water, roughly pH 4.5 to 7. Carbon dioxide in the 25 to 40 mg/l range is recommended to keep the leaves richly coloured, and nitrate and phosphate should stay available. Under weak light or poor nutrition the red fades toward green. Propagation is by cuttings, as with most stem plants. Its slow pace and picky water make it a plant for experienced keepers rather than a beginner choice.