Hygrophila corymbosa ''Angustifolia''

Hygrophila corymbosa "angustifolia" is a narrow-leaved variety of the highly variable species H. corymbosa. It is native to South-East Asia, where it grows emersed as well as submersed in slow- to fast-flowing waters. In aquaristics, it is not as widely spread as the related H. corymbosa varietys "siamensis" and "stricta".
It is most often found in trade under the name "Hygrophila angustifolia", however, it is not identical with the botanical species H. angustifolia, which is related to Hygrophila salicifolia, not H. corymbosa.

The emersed shoots of H. corymbosa "angustifolia" have opposite lanceaolate leaves of a dark to blueish green colour 10 cm long and 2 cm wide, more or less hairy, and when touched they give off a somewhat pungent smell. Branching flower stalks develop in the leaf axils, the light blue/violet flowers are quite beautiful.
Submersed plants form light green leaves, narrower and considerably longer than those of the emersed form (up to 20 cm long and 1 cm wide), completely without hairs.

Cultivation is quite easy, given that the plant's basic requirements are met. Sufficient light and an ample CO2 supply are predominant, however, under strong lights it needs a lot of nitrate, phosphate, potassium and trace elements. Its rapid growth makes it an ideal indicator plant for diverse nutrient deficiencies. If there is not enough potassium, e.g., its leaves develop small black spots and later on holes, nitrate deficiency causes its older leaves to turn yellow and die off, whereas pale, almost white new leaves are an indicator for a lack of iron.
H. corymbosa "angustifolia" benefits from a slight current, which brings its beatiful undulate foliage out especially well.

Good light intensity and an ample supply of nutrients induce enormous growth rates and impressive foliage in this plant. Propagation is easy, just cut off and re-plant lateral shoots or the top shoot, like you would do with most stem plants. The more trimming the plant gets, the bushier will its growth develop.
When allowed to grow to and above the water surface, the air shoots will assume their emersed form. Like other varietys of C. corymbosa, beautiful blue/violet flowers will form on branching flower stalks outside of the water.
Occasionally, newly-bought plants that were grown emersed in the nursery might have difficulties adapting to submersed cultivation.

With its long, elegant leaves, H. corymbosa "angustifolia" lends itself to accentuating the background of large aquariums, where it contrasts beautifully against broad- or round-leaved plants. It is also very well-suited for central, free-standing mound arrangements in aquascape layouts, where its undulate leaves sway gently in the slight current.