Biology  Modes of Multiplication 

Multiplication - predominantly vegetative.  Intensive growth occurs from June through August.  Plants double the mass of their body in 1 - 6 days, and the doubling of frond number occurs in 2 - 3 days.  Mode of pollination - cross-fertilization, with the aid of the wind or insects. 

Flowering of duckweeds

At the initiation of flowering, fronds are always located on the surface of the water, with air chambers more developed than in the vegetative state.
 

Vegetative fronds of Lemna gibba.

 Flowering fronds of Lemna gibba.

The period of flowering, from the moment of the initiation of flowering fronds to the end of floral development, is about 20 days. 
 
As duckweed prepares for flowering, the volume of the fronds increases.

 

Flowering fronds of Lemna, Krasnodar, 1995
 
Common form of inflorescence of Lemna minor
Common form of inflorescence of Lemna trisulca.

 
Stigma of the first flower of Lemna gibba.

 
The stigma and the stamen of the 2nd male flower of Lemna. Bottom view of flowering fronds of Lemna gibba.

 
Newly emerging fronds in flowering duckweed are as ready for flowering as the maternal
                                frond.  Evidence for this is the swollen air cavities in the young frond. 

 
Flowering fronds of Lemna minor.
 In contrast to L. gibba flowering L. minor does not increase the dimensions of its fronds. 

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Краснодар, 2002