The Gibberellins 



103 



Fig. 6-2. Effects of various gibberellins on flowering of the LDP lettuce 

 (Lactuca sativa var. Grand Rapids) on short days. From left to right: controls 

 (vegetative), and gibberellins A x (flowering), A 2 , A 3 , and A 4 . Plants were 

 treated with a total of 4 applications of 10 microliters of 10~ 3 M solutions at 

 weekly intervals starting when 6 to 8 true leaves were present. (Photograph 

 courtesy of Dr. M. J. Bukovac, Michigan State University.) 



flowering. Examples of such plants are Roman nettle (Urtica 

 pilulifera) and enchanter's nightshade (Circaea lutetiana) (Lona, 

 1956). Since most of the widely studied LDP are rosette plants, 

 the notion that gibberellin promotes flowering in all LDP has been 

 current but is probably untrue. Not even all rosette plants tested 

 have proved responsive. 



