Ludwigia arcuata: The Needle Leaf Ludwigia

Ludwigia arcuata, commonly known as Needle Leaf Ludwigia or Narrow-leaf Ludwigia, is an elegant and highly desirable aquatic stem plant/tissue cultures prized for its slender leaves and potential for striking red and orange coloration. Native to the wetlands of the Southeastern United States, this species exhibits a delicate beauty that can dramatically enhance an aquascape.

When grown submerged, the leaves of Ludwigia arcuata become exceptionally narrow and pointed, arranged in neat pairs along a relatively thin stem. Under optimal high-tech conditions, the entire plant, especially the crown, will transition from green or yellow-orange to a deep, fiery red or reddish-brown, making it a fantastic color accent for the midground or background.

While often described as having an easy to moderate care level, achieving the full, bushy growth and intense red color requires attention to high light intensity and controlled nutrient levels, making it a better choice for hobbyists familiar with planted tank maintenance.

Care & Coloration Profile:

• Difficulty: Intermediate. It is generally hardy, but demands high light and specific nutrient conditions to achieve its best color and density.
• Growth Habit: It is a Stem Plant. It grows at a moderate rate, up to 20 inches (50 cm) tall, and tends to branch out when pruned, allowing it to be sculpted into a dense, attractive bush.
• Lighting: High (Essential for Red). Medium to high light is required. High PAR values (ideally 100μmol or higher) are crucial to trigger the production of red pigments (anthocyanins). Under lower light, the plant will remain green or become leggy.
• CO₂: Highly Recommended. While some sources say it's not strictly necessary for survival, CO₂ injection (around 30ppm) is essential for rapid, dense growth and for achieving the deepest red coloration.
• Nutrient Strategy for Color: Low Nitrate (NO₃). This is one of the few red plants that becomes significantly redder under a nitrate-limiting condition (Nitrate levels below 5ppm in the water column). To maintain healthy growth while limiting nitrates, it's highly recommended to use a nutrient-rich aqua soil or root tabs to supply necessary nitrogen through the roots. Consistent iron and micro-nutrient dosing are also beneficial.
• Water Parameters: Prefers a tropical environment with a temperature range of 68−82°F (20−28°C) and a pH of 5.5−7.5. Stability is key, as the plant can melt when exposed to sudden, drastic water parameter changes.
• Placement: Best used in the midground or background of the aquarium. Frequent trimming allows it to be maintained as a dense, colorful shrub.
• Propagation: By stem cuttings. Simply trim the top few inches off healthy stems and replant them into the substrate to create new plants and encourage the original plant to sprout side shoots for a bushier look.

Quick Facts

• Scientific Name: Ludwigia arcuata
• Primary Common Name: Needle Leaf Ludwigia
• Other Common Names: Narrow-leaf Ludwigia, Pond Seedbox
• Origin: Southeastern United States (North America)
• Max Size: Up to 20 inches (50 cm)
• Temperament: Peaceful (Aquatic Plant)
• Diet: Heavy Root Feeder (Benefits greatly from rich substrate)
• Minimum Tank Size: 10+ Gallons
• Aquarium Placement: Midground / Background
• Coloration: Red, Orange, Green (Deep red requires High Light and Low Water Column Nitrates)