EXPERIMENTS IN FORCING NATIVE PLANTS TO 

 BLOSSOM DURING THE WINTER MONTHS 



C. O. ROSENDAHL 



University of Minnesota, Minneapolis, Minn. 



The problem of obtaining sufficient and suitable material 

 for class work in taxonomy during the winter months, especially 

 of flowering plants, is often a very perplexing one to those giving 

 instruction in schools and colleges of the northern states. Dried 

 and pressed specimens are generally unattractive and unin- 

 structive to the average college student of systematic botany, 

 and it is only the occasional person with a predilection for taxo- 

 nomic work who can sustain his enthusiasm on this kind of ma- 

 terial alone and derive benefit from it. Material preserved in 

 alcohol or formalin, though much better for dissection purposes, 

 is bound to be both sloppy and smelly, and on the whole not 

 much more desirable or satisfactory than the first mentioned kind. 

 Formalin material becomes particularly objectionable if the 

 plants are large and a considerable quantity of it has to be given 

 out at one time. 



If one is fortunate enough to have extensive greenhouse space 

 for growing plants that blossom during the winter season, these 

 difficulties can be lessened to a considerable extent by supple- 

 menting with fresh flowers and plants. However, this kind of 

 material is not wholly satisfactory either, for the reason that 

 most of the winter-blooming hothouse plants are strange exotics 

 and frequently are not representative of families and genera with 

 which the average student comes in actual practical contact. 

 They also present often the additional difficulty of being double 

 or filled to such an extent that they prove of little or no value 

 for systematic work. 



Finally, our manuals and floras, available as handbooks for 

 students of taxonomy, include but a very few of the hothouse 



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