Water wisteria
Hygrophila difformis
Water parameters
Light and nutrients
Substrate type: any. Propagation: cuttings.
Substrate compatibility
| Substrate | pH effect | Nutrient load |
|---|---|---|
| Inert sand (Pool filter sand) | neutral / inert | none |
| Inert gravel (Aquarium gravel) | neutral / inert | none |
| Aquasoil (ADA Amazonia) | lowers pH | very high |
| Mineralized clay substrate (Seachem Fluorite) | neutral / inert | moderate |
| Dirted tank (mineralized topsoil) (DIY soil substrate) | slightly acidic | very high |
With fish
Origin and habitat
Hygrophila difformis is an amphibious member of the family Acanthaceae (order Lamiales), with a native range running from eastern Nepal through Myanmar and Sri Lanka and reaching northern Australia, where it grows in marshes and shallow, seasonally wet ground. Older aquarium literature often lists it under the synonym Synnema triflorum. The plant is famous for heterophylly: above water it carries simple, oval leaves with toothed margins, but once submerged it switches to deeply dissected, fern-like foliage, one of the more extreme leaf-form changes among aquatic plants. Recent genetic work has tied that switch to developmental regulators including a SHOOT MERISTEMLESS gene, and a published genome assembly now exists for the species. Submerged leaves reach roughly 8–15 cm across and give the stems a lacy, bushy look as they branch. It has been an aquarium staple since the 1960s. Because farm stock is usually grown emersed, freshly bought plants drop their simple leaves over a week or two and regrow the lobed submerged form; the temporary leaf loss can look like the plant is dying but is normal.
Outdoor pond use
- USDA zones
- 8–13 (winter low around -12°C or warmer)
Care notes
Easy and quick. It grows across a wide light range without added CO2 and in soft to moderately hard water near 20–28°C. Brighter light produces the compact, fully lobed leaves that make it attractive, while dim light gives taller, leggier stems with simpler foliage. Push stems into the substrate in small groups. Growth runs fast, on the order of several centimetres a week in good conditions, so topping and replanting weekly is normal; cut stems throw side shoots and fill in densely. That speed makes it a strong competitor against algae and a useful nutrient sink in new or overstocked tanks. Feeding is moderate; without enough nutrients the older leaves pinhole and yellow, which liquid fertiliser prevents. The divided leaves give fry and shrimp good cover. Propagation by cuttings is reliable, and the plant is cheap and widely stocked.