106 BRITISH PLANTS 
xerophytes ; some climb, some have succulent leaves, 
others leaves hoary with hairs ; one has leaves like ivy, 
another leaves like flax, another leaves like heath ; but 
the flowers are the same in all. 
In Part II. we have to deal chiefly with biological 
divisions based upon functional similarities and dis- 
similarities. Land-plants, for example, will be divided— 
1. According to their Longevity (Chapter XI.). 
2. According to their Frequency of Seeding (Chap- 
ter XI_.). 
3. According to their Mode of Growth (Chapter XII.). 
4. According to their Mode of Nutrition (Chapter XIIZ.). 
