FORCING NATIVE PLANTS TO BLOSSOM 355 



plants, and consequently the training of running down and de- 

 termining species has to go by default. This undoubtedly is 

 the most serious objection to exotic material for I believe that 

 it must be generally conceded that one of the chief values of a 

 course in taxonomy is the training afforded by continual practice 

 in the independent determination and classification of genera 

 and species. If manuals were available with good keys and 

 brief diagnostic descriptions, covering the majority of the plants 

 usually grown in our greenhouses, then there would be less 

 objection to using these plants very largely as regular material 

 throughout the time of the year when native vegetation is 

 dormant. 



In looking about for a way of obviating, at least in part, the 

 various difficulties pointed out above, the feasibility of forcing 

 native plants to blossom during the winter months suggested 

 itself to the writer. When this plan was first suggested to the 

 head gardener, an Englishman of long experience, it met with 

 considerable skepticism and was looked upon with more or less 

 disfavor as a waste of valuable time and greenhouse space. 

 After considerable persuasion and delay, the experiment was 

 undertaken and carried through according to the plans and sug- 

 gestions of the writer. Naturally after the authoritative dis- 

 couragement of the gardener, little or no success was really antici- 

 pated from it, but it proved on the whole so successful that a 

 brief account of the methods employed and an enumeration of the 

 plants used are deemed justifiable. 



All the plants used were found growing naturally in and 

 around Minneapolis. They were dug late in the fall of the year, 

 after the growing season was over, and replanted at once in pots 

 and flats of suitable size and depth. . The pots and flats were 

 used more or less indiscriminately, largely for the reason that it 

 was not known which would prove the most satisfactory. After 

 a year's trial it was demonstrated that for most of the plants, 

 the flats were the best, mainly because they afforded the roots 

 more space in which to spread out and take hold. Furthermore, 

 the flats can be frozen without danger of breaking, and there- 

 fore in the end save both time and expense. No definite attempt 



