Updated: Jan 3, 2020
Wolffia is a genus of duckweed which are considered the world's smallest of flowering plants (angiosperms). Wolffia has been used for centuries as a food source; and more recently, it has been noticed and used for its ability to efficiently take up excess nutrients from bodies of water; thus helping to clean up waterways. This ability also makes it a highly nutritious plant.
Wolffia globosa, or watermeal, is native to Asia but is also found in the Americas. It grows well in calm bodies of water and provides food and shelter for thousands of species. Due to its ability to take up nutrients, it is considered quite nutritious, in fact, that it has been dubbed by some as a vegetable meatball. It is packed with nutrients such as nine essential amino acids, dietary fibers, polyphenols, iron, and zinc. Researchers in Israel have created a high protein yielding duckweed called Mankai which has proven to offer a variety of health benefits.
Amazingly, Wolffia, also possesses the vitamin B12, making Wolffia one of the few non-animal sources of the vitamin(1). Bacteria and some fungi are the only lifeforms we know of that produce biologically active B12. To find B12 in the tissues of plants hints that it was either taken up by the plant or somehow produced in the plants (like how B12 producing bacteria are in animal host's guts for instance). However, it has been known for some time that the Wolffia genus have a symbiotic relationship with the cyanobiont, Anabaena azollae. This bacteria is actually photosynthetic and produces B12 (2). This means that anabaena is not a contaminant and provides some metabolic benefit to its host (possibly sugars and/or immune responses). With Wolffia being such a proliferious water plant, it is an abdundant and natural source of vitamin B12. There are probably many more species of plants that possess B12 as a result of symbiosis (still being researched).
More interesting facts about Wolffia is below in the links and video below:
Mic the Vegan discusses this as well:
Thank you for reading!