6 



CIRCULAR NO. 115, BUREAU OF PLANT INDUSTRY. 



nonhardy types under his observation have " compact, upright- 

 growing crowns, with comparatively few buds or shoots below the 

 surface of the soil"; while certain of the hardy types are "char- 

 acterized by a more spreading crown, with buds and shoots springing 

 from the crown below the surface of the soil." He has not only 

 observed these underground buds, or shoots, as he calls them, but cor- 

 relates them with drought resistance and hardiness. Furthermore, 

 lie notes the tendency of the rhizomes to take root at some distance 

 from the old crown and produce new plants. No detailed descrip- 

 tion, however, is given by him of these underground growths or the 

 manner or time of their development. 



Oliver, in his work with numerous alfalfas, including natural and 

 artificial hybrids of Medicago satioa and M. falcata, developed some 



Fig. 1. A plant of hybrid alfalfa six months from the seedling stage. The prominent 



growths appearing below the crown are rhizomes; in other words, true stems. (From 

 Bulletin 258 of the Bureau of riant Industry, by George W. Oliver.) 



exceedingly interesting material. 1 He finds that there are two gen- 

 eral types of rhizomes produced — rooting and nonrooting— and that 

 during the early stage of their development they appear to be of the 

 same character. He also finds that both types of rhizomes are pro- 

 duced most abundantly during the autumn months and that they 

 originate at or near the crown of the plant, one case only coming 

 under his observation where they were produced below the surface. 1 ' 

 In this case the rhizome was at least 3 inches below the crowu. 

 Oliver gives a rather detailed description of the gross morphology 

 of the rhizomes, their life history, and functions. His descriptions 

 and photographs show positively that the underground growths 

 which he describes are true and modified rhizomes, according to the 

 accepted definition of the term. In other words, they are of stem 

 origin. (Fig. 1.) 



1 Oliver, G. W. Op. tit. 

 [Cir. 115] 



Oliver, G. W. Op. cit., p. 22, PI. X, fig. 2. 



