156 



STEMS 



A . Rhizomes. — The word means root-like. Rhizomes 

 sometimes form the entire stem system of the plant. 

 Some violets and nearly all ferns have ho true stems above 

 ground. The leaves arise directly from the stems and are 

 lifted into the air by their petioles. It is more common, 

 however, for rhizomes to give rise to true stem branches. 



These, of course, push up into 

 the sunlight instead of re- 

 maining in the ground. Such 

 ^branches are negatively geo- 

 tropic instead of transversely 

 geotropic Uke their parents. 

 They bear leaves and flowers 

 and manufacture food. Much 

 of this food is stored up in the 

 rhizome to be used in the for- 

 mation of young shoots in the 

 following season. The rhizome 



Fig. S3. — A single plant and the perennial rhizome of the May apple or mandrake. 

 The rhizome is several years old, the growth of each year being marked by a clus- 

 ter of roots. — Redrawn from Bergen. 



itself is perennial. The ferns and many of the early spring 

 flowering plants arise from perennial rhizomes. The May 

 apple or mandrake, the bloodroot, the violet, the trillium, 

 and the Solomon's seal all have this habit. (See Figure 

 5J.) Iris and water lily also grow from rhizomes. It 1= 



