'JIIF. AM l-.RICAN BOTAXIS'I 171 



l-'i-KKCTs oi' Ijc.iiT ON P'kiitixc.. — Nearly c-veryhocly has 

 iiolicfd tlic tcndciicx' (»t plants lo hlooni most profusely <lMr- 

 in,!4' tlie colder parts of tlu' year. Winter, instead of summer, 

 sliotdd l)e represented as ii^arlanded witli flowers. Summer 

 has its blossoms to he sure, hut the [)rotusion of lli)\\ers in 

 autumn is exceeded only hy liie hurst of bloom in the spring. 

 While most of the plants that bloom during the cooler part 

 of the year are restricted to one or the other of these seasons, 

 there are a few, such as the violets, that bloom both in spring 

 and autumn or perhaps they bloom from autumn to si)ring and 

 are re[)ressed only temporarily hy the coldest weather. There 

 is, however, a considerable body of e\ idence to show that it 

 is the shortness of the day, rather than the cold that induces 

 blooming. 'l\vo Government botanists, W. W. Garner and 

 II. A. Allaid have been coiulucting a long series of experi- 

 ments which seem to settle the matter. They fuid, however, 

 that plants may be divided into two different categories as re- 

 gards their response to different periods of daylight. In one, 

 a long period of light induces flowering; in the other it hinders 

 the process. Acting on this knowledge, they have been able 

 to bring the spring flowering Viola fimbriafa into bloom a 

 second time in Julv bv simply reducing the length of time the 

 plant is exposed to the light each day. On the other hand, 

 the rose mallow, (Hibiscus inoschcutos) which normally 

 blooms in sununer, was not able to flower at all when its light 

 exposure was cut down to seven hours daily. ?^-om this the 

 gardener ought to get a hint on growing superior salad-plants. 

 Lettuce and spinach are noted for "rimning to seed" in late 

 spring and early summer, hut l)y reducing their supply of day- 

 light this tendency is quite eradicated. In the case of the scar- 

 let globe radish which, planted in May, was deprived of some 

 hours of light daily, it continued to vegetate through the sum- 



