Hydrocotyle tripartita 'Japan' - Tissue Culture

Hydrocotyle tripartita 'Japan': Japanese Pennywort

The Japanese Pennywort, often sold as Hydrocotyle 'Japan', is a popular, fast-growing, and highly versatile aquarium plant/tissue culture that has become a staple in modern aquascaping, popularized by artists like Takashi Amano. Its small, vibrant green, clover-like leaves give it a unique texture, which contrasts beautifully with finer-leaved or red plants. Although the 'Japan' cultivar is commonly traded, the species itself originates from areas spanning Australia, New Zealand, and Southeast Asia.

This plant is incredibly adaptable in its placement. It spreads quickly by sending out runners along the substrate or hardscape. When given high light and regular pruning, it stays low and forms a dense, lush carpet in the foreground. If left to grow, it can form thick, cascading bushes in the midground or trail elegantly over rocks and driftwood. Its rapid growth makes it an excellent plant for consuming excess nutrients, thereby helping to keep the water column clean and deterring algae outbreaks.

Care & Planting:

• Lighting: Medium to High. While it tolerates medium light (where it grows taller and less dense), high light is essential for achieving the prized, short, and compact carpeting effect.
• CO₂ Supplementation: Recommended. CO₂ injection dramatically increases its growth speed and lateral branching, resulting in the desired bushy, dense appearance. Without it, growth is much slower, and the plant tends to be more sparse. Ideal CO₂ concentration is around 20−30 ppm.
• Fertilization: Water Column and Root Feeder. Due to its fast growth rate, it is demanding of nutrients. It benefits significantly from a nutrient-rich substrate (aquasoil or root tabs) and consistent liquid fertilizer dosing. Yellowing leaves are often the first sign of nutrient deficiency, particularly a lack of micronutrients.
• Planting: Runner/Stem Plant. Separate the runners into small tufts, ensuring each piece has a few root nodes. Plant the clusters lightly into the substrate, allowing adequate spacing (about 1.5 inches) to allow the runners to fill in and form a carpet. It also attaches easily to rough surfaces like wood and rock.
• Pruning: Frequent. To maintain a low carpet or bushy shape, frequent trimming (every 1-2 weeks in a high-tech tank) is necessary. Trimming encourages the plant to branch out horizontally and thicken, while preventing it from completely overgrowing the aquascape. Cuttings can be easily replanted to expand the carpet.

Quick Facts

• Scientific Name: Hydrocotyle tripartita (often sold as 'Japan')
• Primary Common Name: Japanese Pennywort
• Other Common Names: Hydrocotyle 'Japan', Clover Plant
• Origin: Australia, New Zealand, Southeast Asia
• Max Height: 2-10 inches (5−25 cm), depending on light/CO₂
• Growth Rate: Fast
• Difficulty: Easy to Moderate
• CO₂: Recommended
• Water Temperature: 68° to 82°F (20° to 28°C)
• pH Range: 6.0 - 7.5
• Placement: Foreground to Midground