54 



HOW PLANTS GROW. 



152. Stipules, as already explained (120), ai-e a pair of appendages at the base of 

 the leaf, one on each side. These often grow fast to the base of the leafstalk, 



as they do in the Ro.;e and in Clover (Fig. 136; si, 

 the stipules). Or they may join with each other and 

 form a kind of sheath round tlie stem, as they do in 

 the Buttonwood and in Polygonum (Fig. 137). 

 Many leaves have no stipules at all. In many 

 cases they fall off very early, especially those that 

 serve for bud-scales, as in Magnolia. 



153. The Arrangement of Leaves on the stem has 



already been explained as to the two principal ways 



(59). Leaves are either 



Alternate, when they follow each other one by one, 



as in the Morning-Glory (Fig. 4) and the Linden 



(Fig. 83) ; or 



Opposite, when in pairs, 



that is, two on each joint of 



stem, one opposite the other, 



as in Maples (Fig. 84). To 



these may be added a third, 



but less common arrangement, 



viz. the 



Whorled ; where there are 



three, foui-, or more leaves on 



the same joint of stem, forming 

 a circle or whorl ; as in Madder and Bedstraw (Fig. 137'). 

 variety of the opposite mode. 



Stipules united. 



137' 

 Wtiorled leaves. 



But this is only a 



Analysis of the Section. 



81. Vegetation very simple in plan, very diversified in particulars. 82. Tlie study of the forms of 

 the organs is Morphology. 



83-89. Roots, their forms and kinds. 84. Primary or original; secondary; how they originate. 

 85. Aerial roots. 86. Aerial rootlets. 87. Air-Plants ; how they live. 88. Parasitic Plants their 

 economy. 89. Shapes of roots : fibrous; fleshy; the principal sorts. 



90. Forms or kinds of stem ; herbaceous, shrubby, arboreous. 91. Culm or straw-stem. 92. Direc- 

 tions or positions of steins. 93. Peculiar sorts. 94. Thorns or Spines, how shown to be branches ; 



