Spirodela polyrrhiza (Giant Duckweed)

17 June 2026

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Spirodela polyrrhiza, commonly known as Giant Duckweed, is a cosmopolitan floating plant found in still waters worldwide. Popular for its rapid growth and nutrient-absorbing qualities, it provides excellent shade for shy inhabitants and helps combat algae. Its distinct, larger leaves make it easier to manage than standard duckweed.

Introduction to Spirodela polyrrhiza

Spirodela polyrrhiza, frequently referred to as Giant Duckweed, is a highly beneficial floating aquatic plant. With a cosmopolitan distribution, it is found in ponds, lakes, and slow-moving waters across the globe. It is highly valued in the aquarium hobby for its ability to rapidly absorb excess nutrients, thereby outcompeting algae and purifying the water.

Care and Maintenance

This floating plant is exceptionally easy to care for, requiring very little in terms of specialized equipment. It thrives in a wide range of lighting conditions, from low to high, and does not require supplemental CO2 injection. Its rapid growth rate means it will quickly cover the water surface, providing excellent shade for low-light plants and a sense of security for shy fish and fry. Due to its larger leaf size compared to common duckweed (Lemna minor), it is significantly easier to scoop out and control when it multiplies.

Aquascaping Application

While floating plants do not fit into traditional foreground or background categories, Spirodela polyrrhiza acts as an excellent supporting plant. Its dangling roots create a beautiful, natural jungle aesthetic at the water's surface while offering hiding spots for surface-dwelling species. Regular culling is recommended to ensure that light continues to reach the submerged plants below.

Plant info

Colors: Green, Light green
Difficulty: Easy
Origin: Cosmopolitan
Usage: Supporting plants
Type: Floating
Growth rate: High
Height: 1 - 3 cm
Light demand: Low
CO2: Low

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