18 PREFACE. 



by casting the language somewhat in a vernacular mould, — perhaps 

 at some sacrifice of brevity, but not, I trust, of the precision for 

 which botanical language is distinguished. 



Arrangement of the Orders. The Natural Orders are dis- 

 posed in a series which nearly corresponds, in a general way, with 

 De Candolle's arrangement (varied somewhat more in this edition, 

 to come nearer to that adopted thus far in Bentham and Hook- 

 er's new Genera Plantarum), beginning with the highest class and 

 ending with the lowest ; and commencing this first and far the larg- 

 est class (of Dicotyledonous or Exogenous Plants) with those orders 

 in which the flowers are mostly provided with double floral envel- 

 opes, viz. with both calyx and corolla, and in which the corolla 

 consists of separate petals (the Polypetalous division) ; beginning 

 this series with those orders in which the several organs of the 

 flower are most distinct and separate (Jtypogynous), and proceeding 

 to those which have the parts most combined among themselves and 

 consolidated with each other (perigynous and epigynous) ; then fol- 

 low those with the petals combined into a monopetalous corolla (the 

 Monopetalous division ; and finally, those destitute of a corolla or 

 destitute of all floral envelopes (the Apetalous division). The class 

 of Monocotyledonous or Endogenous Plants opens with orders ex- 

 hibiting one form of simplified flowers, passes to those with the or- 

 gans most combined and consolidated, then to those less combined by 

 adnation of parts, and closes with other simplified and reduced forms. 

 The present problem in Botany is to group the numerous Natural 

 Orders in each class into natural alliances. But this has not yet 

 been done in such a manner as to be available to the ordinary stu- 

 dent. I do not here attempt, therefore, to group the orders naturally, 

 but let them follow one another in what seems to be on the whole 

 a natural and manageable sequence. And, by means of an artificial 



Analytical Key to the Orders (p. 21), I enable the student 

 to refer readily to its proper order any of our plants, upon taking 

 the pains to ascertain the structure of its flowers, and sometimes of 



