Hygrophila odora

It seems that this Hygrophila species is so far the only one in the aquarium hobby that is endemic to Africa - although this genus includes quite many exclusively African species. Hygrophila odora grows in wetlands of West Africa, e.g. on riversides.
Hygrophila odora shows a great difference between the emersed and submerged forms. In the emersed form, it is a strong marsh plant that grows to a height of almost one metre. The upright shoots have lanceolate leaves with entire margin and striking large blue-violet flowers in the upper leaf axils, which are somewhat reminiscent of sage (Salvia) flowers. The emersed stems and leaves are covered with sticky glandular hairs and have a strong odour, hence the species name H. odora.
In the submerged form, however, the plant is light green, hairless and has very decorative pinnately cut, narrow, almost fern-like leaves up to 10 cm long on tough stems. This Hygro species grows relatively slowly submerged and is well suited for moderately tall bushes in the aquarium midground.

Hygrophila odora is quite demanding with regard to the macro- and micronutrient supply. It is known to have a higher need for phosphate whose concentration in the water should not fall below 0,3 mg/l. Also CO₂ supply and rather soft water with a carbonate hardness up to 6 °dH are recommended. The favourable temperatures lie between about 23 and 28 °C. Medium lighting is sufficient, however the plant must not be shaded. It is best planted in a group of single stems with a little space to each other. Occasional trimming of the shoot tips promotes more bushy growth. Hygrophila odora can be propagated by cuttings of the stem tips and side shoots, as well as other stem plants. Stems floating at the surface develop many side shoots that can be used for propagation. If you want to cultivate the plant emersed, rather strong lighting and a nutrient-rich substrate are recommended.

This rare African Hygrophila looks best as a group in the midground, in larger aquariums also in the foreground. With its pinnatisect, light green foliage, it gives a particular accent, and its relatively slow growth makes it easier to handle than Hygrophila difformis and H. balsamica with similar pinnate leaves. Hygrophila odora is also interesting as emersed plant for spacious paludariums where one may expect its pretty flowers.