How to grow Hygrophila difformis [Water wisteria]

Introduction

Hygrophila difformis, commonly known as water wisteria, stands as a popular aquarium plant from the Acanthaceae family. This amphibious species has remained a staple in aquarium keeping since the 1970s due to its adaptable nature.

Water wisteria displays heterophylly, whereby plants alter their leaf structure based on environmental conditions. This adaptation mechanism allows the plant to optimize its form for different growing conditions.

Emersed grown leaves (left) vs submerged grown form (right).

Native to the wetlands of South and Southeast Asia—including India, Bangladesh, Thailand, and Malaysia—H. difformis has different leaf shapes under different moisture conditions. Under terrestrial conditions, the plant produces broad, oval-shaped leaves with serrated edges. However, when submerged in aquarium conditions, the leaves transform into finely dissected, lacy structures measuring 6-12 cm in width.

The plant entered aquarium culture during the 1970s, where its relatively undemanding care requirements and steady growth characteristics made it especially appealing to novice aquarists.

Variegated varietals of this species exist, showcasing white veins on the leaves.

Similar Species

Water wisteria is often confused with water sprite (Ceratopteris thalictroides), although several characteristics distinguish these species. Water sprite exhibits a central rhizome growth pattern, while water wisteria develops through stem and root systems. Although both species grow at reasonable rates, water wisteria produces narrower, more densely arranged foliage that provides better structural stability in aquarium environments.

The leaf structure differs between species: water sprite maintains consistently fern-like fronds regardless of environmental conditions, whereas water wisteria's heterophyllous nature allows for very different looking emersed grown vs submerged grown leaves.

Water wisteria also demonstrates better anchoring capabilities compared to water sprite, which can become dislodged in moderate water flow conditions. 

Aquascaping Placement

Water wisteria can work as a background or midground specimen, where it reaches its eventual height of 20-40 cm. It is a rather messy plant to aquascape with due to its aggressive and wild growth form, and it has low popularity among the aquascaping crowd. However, it is popular among more casual hobbyists due to its ease of care.

The plant can be pruned at the top to force side shoots to form from its lower internodes. This can create a bush that is fuller at the bottom. In higher light levels, H. difformis stem will creep along the substrate. In low light levels the stem will grow more vertical.

How to grow

Water wisteria grows well under with at least moderate lighting conditions, with 50-80 μmol of PAR producing good leaf development. Under insufficient illumination, internodal spacing increases, creating elongated growth patterns that may compromise visual appeal. 

It tolerates a wide range of temperature and is suitable for warm tanks and tropical temperatures, growing well in 20-30°C+. H. difformis can be grown well in both soft, acidic water and alkaline hardwater tanks. This makes it suitable for virtually any freshwater tank except for brackish setups. This makes it one of the most ubiquitous aquarium plants available in the hobby. As an aggressive grower, having ample nutrient supply either through the substrate or water column greatly speeds up its growth.

Even thought it is a hardy plant, nutrient or carbon insufficiency can still stunt its growth. Transplant shock manifests as deterioration of older leaves following relocation or repropagation attempts. However, this represents normal adjustment rather than cultivation failure. New growth typically resumes within 14-21 days as root systems reestablish and the plant should produce new leaves as it adapts to the new environment. Older deteriorating leaves should be cut off to prevent algae from attaching to the plant.

Trimming and Propagation Techniques

Vertical growth can be controlled by cutting off the apical bud. This promotes lateral branching from further down the stem. This results in bushier specimens that maintain better structure within aquascape compositions. When trimming, cut stems 3-5 cm below the desired height, ensuring cuts occur between leaf nodes to minimize tissue damage.

To propagate, identify healthy parent stems reaching 15-20 cm height. Using sharp aquarium scissors, cut 10-12 cm sections ensuring each cutting contains 3-5 leaf nodes. Remove lower leaves from the bottom 3 cm of stem, then plant cuttings 2-3 cm deep in substrate. New root development typically occurs within 7-10 days under good conditions.

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