Duckweed Geography

A Map of Duckweed Distribution
 

Each dot indicates an area of duckweed occurrence. Legend for numbers:  The occurrence of Lemnaceae lacking due to: 1 = too dry,  2 = too wet,  3 = too cold,  5 = not sufficiently explored [ Click on map for a high-resolution image ]

The above figure is from Landolt, 1986, p. 234.

Duckweeds have been found on every continent, save Antarctica.  Regions lacing duckweeds are indicated by numbers on the map (see legend).  In particular, certain regions (Brazilian rain forest, Siberia) may not have been sufficiently explored by botanists.

Environmental Adaptation in Three Lemna Species

The extreme range of proliferation of the duckweeds as a group does not mean that are they are equally well-adapted to all conditions.  Each genus and species of duckweed has a characteristic distribution.

Three species in the genus Lemna are a good example:
 

Lemna gibba	Mainly in regions with a Mediterranean climate (dry, mild) and tropical mountains, except Australia
Lemna minor	Probably native to cooler regions of North America, Europe and western Asia.  Occasionally found elsewhere, probably introduced by human activity
Lemna turionifera	Mainly found in North America, occasionally in Eurasia The only Lemna species that can form turions

The above figures are modified from Landolt, 1986.  Click on maps for a high-resolution image.

Wolffiella is known only in America and Africa, but Spirodela, Lemna and Wolffia are found world-wide.  Spirodela has its greatest diversity in South America, while Lemna is most diverse in North America and Southeast Asia.  Wolffia occurs mainly in America, Southeast Asia and Australia.  Wolffiella is mainly subtropical. (Landolt, 1986, page 233).  For North American distribution maps of many species [ link ].  The the area of greatest diversity for a given species is generally thought to represent the area where that species originated.  See Duckweed Evolution.

Read how duckweeds survive harsh conditions: cold, drought and salinity stress.
 

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Revised:  August 5, 2006