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. 



il# 42. The stem 



may be simple or 

 branched. (Figs. 20, 

 21.) A simple stem 

 usually grows from 

 the terminal bud, 



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 



