KINDS OF STEMS 



15 



Spruces always grow to a single stem 

 or trunk, pear trees are always deli- 

 quescent, morning-glories are always 

 climbing, strawberries are always 

 creeping. We do not know why each 

 plant has its own habit; but the habit 

 is in some way associated with the 

 plant's genealogy or with the way in 

 which it has been obliged to live. 



42. The stem 

 may be simple or 

 branched. (Figs. 20, 

 21.) A simple stem 

 usually grows from 

 the terminal bud, 



21. Branched stem of alfalfa. 



20. Simple stems of sorghum. 



and side branches either do not start, or, 

 if they start, they soon perish. Mul- 

 leins are usually simple. So are 

 palms. 



43. Branched stems may be of 

 very different habit and shape. 

 Some stem systems are narrow and 

 erect: these are said to be strict. 

 Others are diffuse, open, branchy, 

 twiggy. 



44. Stems vs. Roots. Roots 

 sometimes grow above ground (31- 

 33); so, also, stems sometimes grow 

 underground, and they are then 

 known as subterranean stems, rhi- 

 zomes, or rootstocks. (Figs. 22, 23.) 



45. Stems normally bear leaves 

 and buds, and thereby are they dis- 

 tinguished from roots. The leaves, 

 however, may be reduced to mere 



