54 



HOW PLANTS GROW. 



i!'' 



152. StipuleS) as ftlroady ex|»laino(l (i 20), are a pair of appendages at the base of 

 the leaf, one on each side. These often j^row fast to the base of the leafstalk, 



as they do in the Hose and in Clover (Fig. 136 ; tify. 

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

 form a kind of sheath round the stem, as they do 

 in the iJnttonwood and in Polygonum (Fig. 137). 

 Many leaves have no stipules at all. In many 

 cases they fall off very early, especially tho.se that 

 serve for bud-scales, as in Magnolia. 



153. The Arrangement of Leaves on the stem ha.'i 



already been ex[)lMined as to the two principal ways 

 (59). Leaves are either 



AUerntdc, when they follow each other one by one, 

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

 (Fig. ?>T,)- or 



Oj>posite, when in pairs, 

 that is, two on each joint of 

 steni, one opposite the other, 

 as in Maples (Fig. 8^). To 

 these may be added a third, 

 but less common arrangement, 

 viz., the 



Whot'Icil ; where there are 

 three, four, or more leaves on 

 the same joint of stem, forming 



a circle or w7< or/; as in Madder and Bedstraw (Fig. 13/). 



variety of the opposite mode. 



IIG 



Stipules \iiiiteil. 



1.17' 

 WliorlfU leaves. 



But this is only a 





h 



Analysis of the Section. 



8r. Vegetation very simple in plan, very diversified in particulars. 82. The study of the forms of 

 the organs in Morpliology. 



83-89. Koots, their fmnis and kinds. 84. Primary or original ; fecondary ; how they originate. 

 85. Aerial roots. 86. Aerial rootlets. 87. Air-Fhuits ; liow they live, 88. I'arasitic Plants, their 

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



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

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



