Pond scum, or is it the world's smallest flowering plant? Wolffia is so small that some species of the plant require a magnifying glass to be correctly identified. Frequently called Watermeal, Wolffia is roughly 1mm long and floats on the top of bodies of calm water. In the winter, this rootless plant sinks to the bottom of its watery home to survive the cold season. Aside from being a popular food for fish, in Southeastern Asia Wolffia is considered a vegetable.
: "Free Floating Plants." Department of Ecology - State of Washington. Accessed May 16, 2016. http://www.ecy.wa.gov/programs/wq/plants/plantid2/descriptions/wol.html.
: "Brazilian Watermeal (Wolffia Brasiliensis)." Illinois Wild Flowers. Accessed May 16, 2016. http://www.illinoiswildflowers.info/wetland/plants/brz_watermeal.html.
: Thompson, C. H. "Wolffia Papulifera." Michigan Natural Features Inventory. 2009. Accessed May 16, 2016. https://mnfi.anr.msu.edu/abstracts/botany/Wolffia_papulifera.pdf.