Biology  Modes of Multiplication 

Fruits and the seeds of duckweeds. 

Flowering and fruit formation in Lemna minor.

Flowering and fruit formation in Lemna gibba.

Fruits of duckweeds are just larger than a poppy seed and are visible to the naked eye.  They are of a form with a pocket or indentations, globular, sometimes longitudinally slightly flattened, not open or split longitudinally, and contain from 1 to 6 seeds. 
 

Ripening seeds in the fruits of Lemna gibba.

Lemna trisulca:  Fruit  Seed
Fruit of duckweed can contain several seeds  ,
and the seeds may be oval  , diamond-shaped 
or of rounded form, as in Wolffia . 
 

Fruits and the seeds of Lemna gibba.  In its fruits one may encounter 3 or 4 seeds.

 

From left to right:  fruit with 4 seeds of Lemna gibba,  and 4 seeds of Lemna minor.