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Question What is the smallest flower in the world?


Watermeal. (Wolffia spp.)

The smallest species of vascular plants in Europe – Spotless watermeal, Wolffia arrhiza – on human fingers. External link Every single speck of less than 1 mm length is an individual plant. Christian Fischer, photographer, 2008. Wikimedia Commons

Watermeal (Wolffia spp.) is a member of the duckweed family (Lemnaceae), a family that contains some of the simplest flowering plants. There are various species of the genus Wolffia worldwide, all very small.

Wolffia.External Prof. Dr. Thomé’s Flora von Deutschland, Österreich und der Schweiz, in Wort und Bild, für Schule und Haus ; mit … Tafeln … von Walter Müller. By Otto Wilhelm Thomâe, Gera-Untermhaus: F.E. Köhler, 1889.  Biodiversity Heritage Library

The plant itself averages 1/42” long and 1/85” wide or about the size of one candy sprinkle. It can weigh about 1/190,000 of an ounce, equivalent to two grains of table salt. They are very hard to see! Imagine if you tried to fill a thimble with them, it is estimated that you would need some 5000 plants!

Bald cypress swamp and duckweed in Lacassine National Wildlife Refuge. Steve Hillebrand,  USFWS  photographer. U.S. Fish and Wildlife Service National Digital Library.

Each Wolffia flower consists of a single pistil and stamen; it also produces the world’s smallest fruit, called a utricle. The plant is found in quiet freshwater lakes or marshes with species worldwide. Since the plants have no roots, they can easily float on the surface of the water, where they resemble cornmeal. Water-meal is sometimes used in cold-water aquaria since it is easy to propagate.

An Upper Mississippi River marina covered by excessive duckweed. James Fischer, Wisconsin Department of Natural Resources, photographer. USGS Multimedia Gallery.

Published: 11/19/2019. Author: Science Reference Section, Library of Congress

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