More than 10 species are found in the aquarium trade, although the existence
of different varieties and the modifications made to scientific names can lead to
confusion. They live half-submerged, but can tolerate immersion in a moderately
hard acid or neutral water. They need intense light to grow well, and should be
planted in groups, but with sufficient spaces between the stems. It is easy to take
cuttings: just chop off the head of the stem as soon as it reaches the surface.
Hygrophila corymbosa (formerly Nomaphila)
The giant hygro tolerates temperatures as low as 15°C. The presence of adventitious
roots is an advantage when taking cuttings. Size: 30 cm.
Hygrophila guianensis (formerly H. salicifolia)
The willow leaf hygro, recognizable by an almost square stem, is sensitive to
excessively hard water or a lack of iron. When the light is insufficient, the leaves
at the bottom of the stem fall off. Size: 30 cm.
Hygrophila difformis (formerly Synnema triflorum)
Considered a weed in its native region, the water wisteria is prized by aquarists
for its pale color and finely serrated leaves, although when these first appear
their form is less delicate. This plant tolerates fairly wide ranges of hardness
and pH. When the leaves drop off the stem, young shoots appear in their place. Size: