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STEMS 



Method of Growth. When the apical bud grows so rapidly 

 that the central axis is the largest and highest part of the 

 plant the stem is excurrent, but when the main stem divides 

 into a number of stems of about equal size, because apical 

 and lateral buds grow equally fast, the stem is deliquescent. 



FIG. 75. Types of Rhizomes. 1, Sweet flag (Acorus calamus) with leaf 

 scars and lateral buds; 2, blue flag (Iris versicolor) with V-shaped leaf scars; 

 3, galangal (Alpinia officinarum) with concentric leaf scars; 4, orris root (Iris 

 Florentina) with indistinct circular leaf scars; 5, mandrake (Podophyllum 

 peltatum) with circular depressed stem scars; 6, false Solomon's seal (Vag- 

 nera racemosa) with circular stem scars and concentric scars; 7 twin-leaf 

 (Jeffersonia diphylla) with contiguous stem scars; 8, geranium (Geranium 

 maculatum) with nodulated surface; 9, Jamaica ginger (Zingiber zingiber) 

 with laterally compressed stem bases and rhizome; 10, bloodroot (San- 

 guinaria canadensis) with indistinct stem scars; 11, quack grass (Agropyron 

 repens) with finely furrowed rhizome and long internodes from which grow 

 buds and roots. 



Modifications, The most important modified stems are 

 (1) rhizcmes, (2) bulbs and (3) tubers. (1) Rhizomes are 



