Art by Alexander Vasiljev, Copyright © 2017


Wednesday, January 22, 2014


Commonly known as water-meal, the genus Wolffia is comprised of a dozen of species of flowering plants belonging to a group of duckweeds from the Arum family (Araceae). Wolffia plants are free floating and unlike other duckweeds do not develop any root system.

Everything about this plant is different and unique. First of all the size. It is the smallest known flowering plant, barely reaching 1 mm in size. Second - it's appearance. Unlike in most plants it has no roots, branches or leaves, instead it possesses a body of undifferentiated vegetative tissue or thallus. The only differentiated part in this plant is a flower that seldom forms in depression on the top of the plant's body. Third - Wolffia's nutritional value. Protein content of this plant can be as high as 45%, placing it in the same league as soybeans.

Wolffia arrhiza, side view

Another Wolffia's "talent" is the ability to propagate with incredible speed. In warm water and under bright light each plant can double its size every 2 days, rapidly taking over any surface of water. Easy cultivation, high yield and nutritional value made Wolffia an important food source for people of South-east Asia, where it is harvested and eaten. Some say it taste like sweet cabbage.

Intervals between the toothpick bristles are less than 1 mm

I have read about Wolffia that it has been cultivated by ranchu breeders in Japan and valued as dietary supplement for ranchu. It is considered easily digestible and contributes to development of head-growth and color (especially yellow). It helps to maintain slim belly, preventing obesity. Adding Wolffia as a food supplement to my ranchu diet sounded like a great idea, especially since I won't be able to raise ranchu in "green water" at least for now.

Wolffia is usually found in lakes and ditches with standing or slow moving freshwater throughout temperate, sub - and tropical areas of the world and usually grows together with other duckweeds like Lemna and Spirodela.

I ordered it online. Wolffia arrhiza was the species that I received. Now I have to be patient, as I can't feed Wolffia to my ranchu quite yet. Since the plants were collected from the outdoor pond, it is necessary to sterilize them and start a "clean" culture with the same microflora as it is in the pond with my ranchu. To sterilize Wolffia I used 2.5% Clorox bleach solution, in which I kept the plants for ≈ 30 sec. Sterilized plants were rinsed in freshwater and transferred into their growing container with water from my ranchu pond. 

These plants need to be fertilized to keep them rapidly growing, but my options were limited. Plant fertilizers won't work, as Wolffia will absorb and retain high concentrations of N and P along with other elements that can harm ranchu if eaten. I wouldn't risk using aquatic plants fertilizers either. My fellow ranchu breeder from Singapore, Wee Yap ( goldfishartquatics.blogspot ) suggested using goldfish dry pellets as fertilizer, and so I did. Nitrates present in my municipal water at 20-40 ppm will provide some additional resource for Wolffia.