CLASSES. 211 



3. You must notice the venation of the leaves, 

 whether they are straight-veined or net-veined leaves 

 (P- 35)- 



4. So also the shape of the leaves, whether they 

 are simple or compound, whether they are entire or 

 notched. 



5. Then as to the structure and manner of growth 

 of the stem. ometimes it is such as I have 

 described in chapter XXX. (Fig. 155, p. 176). This 

 kind of stem you remember has been called exogenous, 

 and so a plant with such a stem has been called 

 an exogens (p. 179). 



But sometimes the fibre-vascular bundles are 

 scattered here and there amidst the fundamental 

 tissue. The stem when cut across shows no regular 

 rings, the fibre-vascular bundles growing wherever 

 within the stem they may happen to be (Fig. 154, 

 p. 176). So this kind of stem has been called endo- 

 genous ; and a plant with such a stem is called an 

 endogens (p. 179). 



6. Then lastly you may notice the number of the 

 sepals, petals, and stamens of a plant whether -they 

 occur in sets of three, or four, or five, etc. 



But remember that though any one of these 

 differences is generally a guide to the class to which 

 a plant belongs, it is not so always. So when you 

 examine a plant, consider as far as you can all the 



