BIENNIALS AND MULTIENNIALS 75 



(2) succulent, when they contain much water, and 



(3) woody, when hard like shrubs and trees, Palms, 



and most vines. 



It must not, however, be supposed that these classes 

 are divided sharply one from another. It is some- 

 times difficult to know whether to call a plant a 

 small tree or a shrub; and in hot countries like 

 India, herbs will often become woody towards the 

 beginning of the hot weather. 



But generally speaking herbs are small plants, less 

 than the height of a man. MUSA, the common Plantain 

 or Banana, is larger, but it is by far the largest of all 

 herbs. Shrubs seldom run up above twenty feet, only 

 some very large Bamboos attaining the height of an 

 ordinary tree. 



