Spirodela

Lore & Background

Spirodela species are free-floating plants whose stems are transformed into leaf-like structures called fronds; each plant is represented by a frond with roots, so they do not have leaves. Two to five plants may remain connected to each other. Plants are green but may turn red due to the presence of anthocyanin. Multiple roots, numbering 5 to 20 depending on the species, emerge from each frond. Spirodela is larger than Lemna, with fronds reaching 10 mm compared to Lemna's 2–5 mm and single root per frond. Certain species overwinter as turions—dormant starchy shoots that lack air pockets and sink to the bottom—then rise to the surface and germinate in spring. Spirodela often forms floating mats with related species such as Lemna and Wolffia. The genus is cosmopolitan in distribution.

Reader's Guide

Spirodela is significant as a representative of the duckweed group, which includes several genera of small aquatic plants. Its larger size relative to Lemna and its multiple roots per frond distinguish it morphologically. The genus's ability to form turions allows it to survive winter conditions in temperate regions, contributing to its cosmopolitan distribution. Spirodela often co-occurs with other duckweeds like Lemna and Wolffia, forming floating mats that are characteristic of still or slow-moving waters. Its classification under the APG II system places it within Araceae, reflecting a taxonomic shift from its former placement in Lemnaceae. The four accepted species as of December 2025 are Spirodela oligorrhiza, Spirodela polyrhiza, Spirodela punctata, and Spirodela sichuanensis. The genus is of interest for studies of aquatic plant biology, overwintering strategies, and phylogenetic relationships among duckweeds.

Did You Know?

• Each Spirodela frond has 5 to 20 roots.
• Spirodela is larger than Lemna, with fronds up to 10 mm.
• Certain Spirodela species overwinter as turions that sink to the bottom.