Helanthium tenellum, also known as the pygmy chain sword, is an undemanding and adaptable aquatic plant. Here are the key details about its origin, light and water conditions, and how to plant it:

Origin

• Native Distribution: North, Central, and South America157.
• Cultivar Origin: Lab-grown tissue culture, but indigenous to North and South America78.

Light Conditions

• Light Requirements: Can grow in medium to low light conditions. The narrow-leaved variety can exhibit rich red coloration under high light intensities, while the broad-leaved variety remains light green even under intense light12.

Water Conditions

• Water Hardness: Can tolerate soft or hard water1.
• pH Range: Can adapt to pH levels from 6.0 to 8.01.
• General Hardness (GH): Can tolerate up to 20 degrees/350 ppm1.

How to Plant

1. Propagation: Spreads by runner chains (modified inflorescences) up to 50 cm in length, with plantlets forming every 2 to 5 cm. These plantlets can be detached and planted separately1.
2. Planting Method:
   • Plant the runner chains or individual plantlets in the substrate, ensuring the roots stay submerged.
   • For optimal growth, use quality aquarium soil and consider adding CO2 and fertilization18.
4. Care:
   • Regularly prune the plant to maintain its appearance and prevent it from invading the tank1.
   • In high-tech tanks, the narrow-leaved variety can quickly become the focal point due to its rich red coloration1.

Additional Tips

• Emersed vs Submerged: If grown emersed, the leaves will be wider and on shorter stems. However, for aquarium use, it is best to keep the roots submerged1.
• Carpeting Variety: The ‘Green’ variety is a small rosulate plant that can easily form a 5-10 cm high carpet when the light is good and the bottom layer is nutritious2.