How does Lemna overwinter?

[Larry D Nooden]

Following up on the earlier answer to this question.  Lemna forms special 
fronds called turions.  These sink in the fall and rise in the spring, 
apparently due to changes in starch composition and gas spaces.  Other 
aquatic plants form turions which are distinctive terminal buds, but 
Lemna turions are very similar to ordinary fronds, just darker green and 
a little smaller.  The book on aquatic plants by CD Sculthore (1967) has a 
lot of descriptive information.  Turion formation in Lemna can make a 
good class experiment.  They are induced by SDs (if you use a SD 
ecotype), and they are induced by ABA/ inhibited by cytokinins.  More on the 
physiology of turions can be found in a chaper on dormant terminal buds 
in ME Clutter's book Dormancy and Developmental Arrest (1973) and Plant & 
Cell Physiol. 17: 721-  (1976).

Larry D. Nooden                           Telephone 313-764-4436
Biology Dept., University of Michigan     FAX       313-747-0884
Ann Arbor, MI 48109-1048
            URL: http://www.biology.lsa.umich.edu/~ldnum/