THE LOW TEMPERATURE PROMOTION OF FLOWERING 71 



perhaps continuing after planting in the spring. Blooming follows 

 rather shortly after flower formation. Examples are Allium cepa, 

 A. escalonicwn, Lilium, and Galtonia. In this intermediate group, 

 optimum temperatures may be rather low (onion, 13°C) or somewhat 

 higher (lily, 23°C). 



D. Flower primordia form after bulbs are replanted in the spring. 

 Examples include Gladiolus, Freesia, and Anemone. Storage tempera- 

 tures seem to have little influence here, and temperatures during 

 formation are difficult to study since initiation and flowering occur 

 in rapid succession in the field after planting. 



Obviously our most important present assignment so far as 

 temperature effects on flowering are concerned, is to begin to gain 

 some insight into the physiological and biochemical mechanisms 

 which control these processes. There is still much descriptive back- 

 ground to be obtained, but we now have a sufficiently broad founda- 

 tion that studies on mechanism should begin to be more fruitful than 

 in the past. These bulbs which are small enough to handle easily but 

 large enough to work with conveniently, and which are uninfluenced 

 by light, might offer an excellent opportunity for research along these 

 lines. It should, however, be quite apparent by now that any desire 

 to understand the operation of a single plant will probably have to 

 be satisfied by work on that particular plant, and findings with other 

 subjects can at best only show the way. 



