- Hardiness: Easy
- Light Needs: Medium
- Plant Structure: Stem
- Family: Acanthaceae
- Genus: Hygrophila
- Region: Asia
- Location: Burma, India, Thailand, parts of Malaysia
- Size: Individual stem width: 5-30cm (2-12 inches)
- Growth Rate: Very fast
- Can Be Grown Emersed: Yes
Hygrophila difformis is a beautiful plant that has been in aquarium cultivation for many years. It can be found growing creeping or erect in marshy habitats in southern Asia, and is ubiquitously available as 'Water Wisteria'. It also was once called Synnema triflorum in the trade. Due to its unchallenged nature, H. difformis is a textbook species for the planted aquarium novice.
Few aquatic plants are easier to cultivate in an aquarium than this species. It grows well under medium light, but higher light encourages larger and more vigorous growth. Coupled with high light and CO2, regular additions of nitrate and phosphate will result in incredibly fast growth. For this reason, H. difformis is an excellent candidate for recently setup planted tanks to absorb excess nutrients. Moreover, the leaf divisions seem to be a little finer (and thus more attractive) under higher light. Water hardness and pH are unimportant, and growth is equally as impressive in aquariums without CO2 supplementation as in those that have it. H. difformis reacts negatively to micronutrient deficiency (especially iron), the signs of which include a pale cast to the leaves as well as sluggish growth. It should be noted that most plants purchased at retail locations have been grown emersed, and it is not uncommon for the first few leaves that grow submersed to retain the shape of their emersed counterparts. This, however, does not last long, and within a few weeks the submersed leaves will form entirely.
Propagation can be accomplished by cutting off the top half of a strong stem and replanting it. The bottom portion will quickly develop new shoots from nodes higher up on its length; this can create a bushy effect if done several times to a number of shoots. Also, new stems frequently develop from nodes on established stems close to the surface of the substrate. In this way the plant can, in effect, creep across an area of the tank.
Due to its potentially large size, H. difformis is inappropriate for aquascapes in smaller tanks. Keepers of larger tanks, however, are extremely fortunate in that they may include this striking plant in their palette. A bushy grouping in a central or rear area of the aquarium can be especially appealing, particularly if it is contrasted with other species of varying leaf shape and color.