16 



GRASSES OP IOWA. 



only after it has extended through the soil for a greater or less 

 distance. These form the "creeping roots" (rhizomes) of 

 grasses, but they are true stems or branches, for they are always 

 distinctly jointed, and at the joints there are scale-like leaves — 

 characters never found in true roots. The joints of these 



Fig. 9. .Japan mlUet {Panicum crus-galli), showing method of furmlng stools. 



underground stems may be very short, and from each node 

 may spring a flowering branch. So condensed may this 

 growth be that the rhizome is entirely concealed, but in peren- 

 nial grasses it is always present, and in the best turf or sward- 

 forming grasses it is sufficiently manifest. In couch-grass, 

 and especially in Johnson grass and cord grass, these rhizomes 



