INTRODUCTION. 



XXV 



Windsor bean, they remain beneath the soil 

 until their office is fulfilled, when they perish. 

 If destroyed prematurely, the young plant dies 



WINDSOR BEAN. 



with them ; in garden-mustard, for instance, they 

 are cut as spring salad, and the plants wither away. 

 As the number of cotyledons is nearly always two, 

 this class is by some botanists termed Dicoty- 

 ledons, Dicotyledons, or Exogens, are subdivided 

 into several suh-classes, and these again into a 

 multitude of orders, the limits of vsdiich it is not 

 necessary to touch on in a work of this kind. 

 Suffice it to say, that each natural order consists 

 of a number of plants assembled, to a certain ex- 

 tent, arbitrarily, though not without regard to their 

 similarity of structure, especially in the organs 

 of fructification. The plants comprised in each 

 natural order are again distributed into genera 

 (families), each genus including all plants which 



