Carolina fanwort

Green Cabomba, also called Carolina fanwort, is Cabomba caroliniana var. caroliniana, a very popular aquarium plant that is easy to find in shops. Its finely forked, lime-green leaves make a good contrast with broader or differently coloured plants at the back of a tank.

Growth is very fast. In good conditions the stems reach the surface of a large aquarium even after hard trimming, and up there they form ovate to diamond-shaped floating leaves and white flowers. The same vigour makes it a problem in open water: it spreads quickly, and Australia treats it as an invasive Weed of National Significance, so trimmings should not end up outdoors.

Light matters more than anything else. If the tank runs too warm or too dim, the stems turn weak and stretched. Flowgrow puts the optimum at 20 to 25 °C with pH 5 to 7, and says pH and hardness count for less than light. Extra CO₂ is not needed, although it will push growth further, and micronutrients can make the plant sturdier. Keeping nitrate low darkens the green, sometimes to brown when the light is strong.

Wild populations live in lakes, ponds and rivers in the eastern United States and south-eastern South America, usually in water with a low pH. Propagate it from cuttings like other stem plants, but expect the cut lower stems to take a while to branch, because side shoots are uncommon on this plant.