Sagittaria subulata

The Narrow-leaved arrowhead is an undemanding grass-like plant for the middle- and background that soon forms dense groups thanks to its underground runners. It may be a bit unpredictable, as it may form a quite short lawn with lots of light and limited nutrient supply, however it develops 30 cm long leaves when the population gets dense and macronutrient supply is good. The submerged leaves are strap-shaped and up to 5 mm wide. In the aquarium it can grow a long flower stalk if the conditions are good. Its small white flowers will open outside the water.

Sagittaria subulata is one of the "longest-serving" aquarium plants. It is ideal for low-tech or no-tech tanks without a CO₂ supplying system; it tolerates a high carbonate hardness, also its light demands are moderate. However Sagittaria subulata is somewhat susceptible to iron deficiency, manifesting in pale new leaves. This aquatic plant from North America is also very temperature tolerant, suitable for tropical as well as cold water tanks. With its low demands, it is particularly recommended for aquarium beginners.

Although it is sometimes recommended as a lawn in the aquarium foreground, it does not remain short in the long run.